Introduction to World Wide Web and Web Development

An introduction of the Web in the first class of IT 5443 at Kennesaw State University - updated in Jan 2019.
About Jack Zheng

Faculty of IT at Kennesaw.edu
Web http http www server en wikipedia org http en wikipedia wikipedia org wiki Web server
An introduction of the Web in the first class of IT 5443 at Kennesaw State University - updated in Jan 2019.
About Jack Zheng

Faculty of IT at Kennesaw.edu
Web http http www server en wikipedia org http en wikipedia wikipedia org wiki Web server
Introduction to World Wide Web 
and Web Development
IT 5443 
Web Technologies and Application Development 
http://it5443.azurewebsites.net
Jack G. Zheng
Spring 2019
This document is hosted at 
https://www.edocr.com/v/qezldpd2/jgzheng/Introduction-to-World-Wide-Web-and-Web-Development
Overview
2
 This lecture notes provide some basic introduction 
to the Web and its fundamental pieces. It also 
introduces good resources to get your further.
 Major topics:
 What is the Web?
 History and evolution stages
 How does the Web work?
 Client server architecture
 Key technology components
 Simple vs. dynamic web
 Client vs. server side
 How to start web development?
 Tools and resources
What is the Web?
3
 The Internet
 A world-wide network of networks and computers 
based on the Internet protocol 
 World Wide Web, or the Web
 Is a client/server application for information and 
services
 Is one of the Internet applications based on the HTTP 
protocol
 The difference between the two?
 http://www.diffen.com/difference/Internet_vs_World_
Wide_Web
Web Related Terms
4
 Web page 

usually refers to a static HTML file, or a dynamically generated HTML document displayed in a 
browser. It resembles a document and mainly informational.
 Web application

a specific functionality-oriented component that utilizes web technologies to deliver information and 
services to users or other applications/information systems.
 Examples: registration, shopping, survey, learning, gaming, etc.
 Web site

a collection of web pages, applications, etc., under a common name and serve a common purpose 
(loosely).
 Web (based) information system

an information system that utilizes web technologies to deliver information and services, to users or 
other information systems/applications.
 A web information system usually consists of one or more web applications, together with 
information components and other non-web components.
 Web service (two different meanings)

Technically: a software component that utilizes web technologies to serve other applications (not 
human users).
 Or in a more non-tech context: a service provided to users through a website.
Evolution Stages
5
Stage
Beginning Time
Features
Pre-web 
Before 1990
All kinds of Internet applications with its specific 
protocols
Early/simple web
Early 1990s
Collection of interlinking web pages. Document
based information retrieval. 
Dynamic web
Mid 1990s
More advanced dynamic processing on both server 
and client side. More functional applications 
emerged.
Web as a 
platform
21st century
A fundamental platform to support all kinds of 
services and integrate various kinds of systems.
Web 2.0 
Since about 2006
Services that support massive user participation and 
contribution.
Redefined client/server communication style.
Greater advancement in software-as-a-service.
Mobile Web
Since about 2010
Major renovation of user experience design and 
application architectures.
Major client-side advancement.
* Note: each later stage does not replace the early stage 
at this time. They only signal the beginning of some 
drastically new developments. The applications of each 
stage are still widely used today.
Pre-Web
6
 Before there was the Web, there was the Internet 
 TCP/IP (Transmission Control Protocol/Internet Protocol) is the key to the 
Internet

Internet applications other than the Web (note Web itself is a kind of 
Internet applications)
 Usenet, BBS, Telnet
 Email, FTP
 P2P, gaming
 Video streaming, instant messaging, VoIP
 Remote control 
 Which Internet application generates the most traffic on the Internet?
 https://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-
networking-index-vni/vni-hyperconnectivity-wp.html
 More from Cisco: https://www.cisco.com/c/en/us/solutions/service-
provider/visual-networking-index-vni/index.html
Extended reading: some history of the Internet 
 https://en.wikipedia.org/wiki/History_of_the_Internet
 http://itwebtutorials.mga.edu/html/chp1/history.aspx
Early Web, Simple Web
7

Invented by Sir Tim Berners-Lee, 1989
 The early simple web focused on interlinking web 
pages/documents for information viewing. 
 5 fundamental elements of the web (see slides later, starting #13, for 
more details about the architecture of a simple web and its 
fundamental elements)
 Web content: HTML (Hypertext Markup Language)
 Web client: browser
 Web server
 Web address: URL (Uniform Resource Locator)
 Web protocol: HTTP (Hypertext Transfer Protocol)
Extended reading: some history of the Web 
 https://webfoundation.org/about/vision/history-of-the-web/
 25 years of the World Wide Web: Tim Berners-Lee explains how it all began: 
http://www.independent.co.uk/life-style/gadgets-and-tech/news/25-years-of-the-world-wide-web-
the-inventor-of-the-web-tim-bernerslee-explains-how-it-all-began-9185040.html
Dynamic Web
8
 Dynamic web refers to the addition of the advanced 
processing power with programming capabilities at 
either server side or client side (or both)
 Because of these powers, more functional 
applications emerged, going beyond just information 
viewing.
 Shopping, registration, survey, learning, gaming, etc.
 More Internet applications began to have a web 
interface
 E-mail, forum (BBS), etc.
 See slides later (#29 to #33) for key technologies 
summary
Web as a Platform
9
 Early Web is a more of an application itself to deliver 
information and service to human over the Internet
 It eventually evolved to an underlying platform that 
supports all kinds of software applications and services
 Applications are developed based on Web technologies and 
standards directly, not OS (think about a Windows application).
 There is no installation on local systems and minimum need for 
OS support.
 Many kinds of applications and services have been brought to 
the Web: e-commerce, multimedia, gaming, socialization, 
communication, etc.
 Connects human-machine, human-human, machine-machine
 Facilitates the standards development and interoperability
https://www.webopedia.com/TERM/W/web_as_a_platform.html
Web 2.0
10
 Web 2.0 is a general and loose concept for the 
advancements of the World Wide Web since 2006

"Web 2.0 is term that was introduced in 2004 and 
refers to the second generation of the World Wide 
Web. The term "2.0" comes from the software 
industry, where new versions of software programs 
are labeled with an incremental version number. 
Like software, the new generation of the Web 
includes new features and functionality that was not 
available in the past. However, Web 2.0 does not 
refer to a specific version of the Web, but rather a 
series of technological improvements." 
http://www.techterms.com/definition/web20
 Key ideas/technologies
 Massive user participation and contribution
 Socialization: connection, communication, networking, 
interaction, sharing
 Collective intelligence: content aggregation, 
crowdsourcing, folksonomy, wisdom of the crowd
 Rich user experience
 Asynchronous client/server communication style
 Software-as-a-service.
https://commons.wikimedia.org/wiki/File:Web-20-
iceberg-model-from-Web20andBeyond-book.jpg
Learning module #11 will cover this topic
https://www.edocr.com/v/gvbmxvzg/jgzheng/Web-20-Overview
(Mordern) Mobile Web
 The popularity of smart phone and tablets pushed the changes of web design on 
small screens and touch based interfaces, and eventually the application 
architecture.

It's mainly about user experience, particularly with a focus on user interfaces and 
interactions.
 Web sites: focus on the display of information adapted to the mobile device
 Web applications: focus on functional features, with UI specifically designed for mobile devices

It impacted the application architecture as well.
 Mobile computing also greatly advanced all aspects of Web 2.0 to a whole new level 
(user generated content, participation, social, collaboration, etc.)
 Overview of mobile web

https://www.edocr.com/v/k52p5vj4/jgzheng/Mobile-Web-Overview

Learning module #12 will cover this topic with more details
11
Mobile web refers to the access and use of web sites and web 
applications over computer networks through web browsers 
using smart mobile devices (and optimized for these devices).
Key Technology Components
12
1. Architecture: Client/Server
2. Client: browser
3. Server
4. Communication protocol: HTTP
5. Addressing: DNS, URL
6. Presentation/UI/content
7. Processing capabilities (server or client 
side)
Client/Server (C/S) Architecture
13
 C/S architecture is a distributed application structure that partitions 
tasks or workloads between the providers of a resource or service, 
called servers, and service requesters, called clients 
(http://en.wikipedia.org/wiki/Client%E2%80%93server_model)
 Note: servers and clients can be installed and work independently (not tied to 
a specific server or client)
Communication 
medium
The medium can be local 
network, internet, or any 
designated channel
Clients and servers are usually 
applications (software), not 
necessarily hardware. They may 
exist on the same computer.
The Internet
Fundamental Technologies in a 
Simple Web Architecture
14
Web server
HTML Files
HTTP -
Response
URL
http://spsu.edu/index.html
Web client: browser 
HTTP -
Request
Server side
Client side
Communication 
medium
HTML (Hypertext Markup Language)
15
 An HTML file (or a web page) is a pure text file created using HTML
 HTML is a standard markup language to describe a web 
document/page using tags (markups)
 All content in a web page are wrapped in tags: <body>, <h1>, <p>, <table>, 
<img>, <a>, etc.
 Web browsers interpret (render) these tags and display the content in a more 
readable format
 Example
 https://www.w3schools.com/html/
tryit.asp?filename=tryhtml_tables
(HTML on the left and browser 
rendering on the right)
 HTML is commonly complimented 
by CSS (cascade style sheet) to 
make web page appearance
Content/Presentation
16
 HTML/CSS is the most common choice to present web 
content and UI to end users
 HTML describes a web document/page using tags (markups)
 CSS (cascade style sheets) takes the styling role from the 
original HTML and is used together with HTML.
 Other UI languages and formats
 XHTML: http://www.w3schools.com/html/html_xhtml.asp
 WML: http://en.wikipedia.org/wiki/Wireless_Markup_Language
 XUL: http://en.wikipedia.org/wiki/Xul
 More: 
http://en.wikipedia.org/wiki/User_interface_markup_language
Are all HTML pages web pages? Not necessarily, examples:
 Local .htm/.html documents

.mht - MIME HTML, a web page archive format, which is used offline

.chm - Microsoft Compiled HTML Help
Client / Browser
17
 A web client presents user interface and interacts with a user.
 Web browser is the most widely-used web client with comprehensive UI features

A browser interprets HTML tags and display the content nicely to users (rendering)

Provides an interface for users

It processes client side scripts and works with other plug-ins

http://en.wikipedia.org/wiki/Web_browser
 Web browser products and market share

http://en.wikipedia.org/wiki/Usage_share_of_web_browsers

http://www.w3counter.com/globalstats.php

http://gs.statcounter.com/

http://www.netmarketshare.com
 Browser/rendering engine: the core part that handles the markups, scripts, and other client processing 
can be integrated into other programs

http://en.wikipedia.org/wiki/Web_browser_engine

Gecko: used in FireFox

Trident (EdgeHTML): used in IE/Edge
 WebKit (Blink): used in Chrome and Safari
 Other types of web client: any application that can process HTTP as an client can be view as a web 
client. Examples:

Embedded browser in a native desktop or mobile application: Visual Studio
 Web service consumer

Hybrid applications which has a component to communicate with the web server

Specific programs without UI: cURL, wget, etc.
Extended reading: a more intensive 
look at browsers: 
https://www.html5rocks.com/en/tut
orials/internals/howbrowserswork/
Web Server
18
 Web server
 Hosts web sites, files (web pages), applications, etc.
 Processes requests from clients (browsers) and send response back to clients
 A web server communicates with clients using HTTP protocol 
 Resources (files, etc.) on web servers are located by URLs.
 Web servers are located by the IP address and domain names.

http://en.wikipedia.org/wiki/Web_server

https://developer.mozilla.org/en-US/docs/Learn/Common_questions/What_is_a_web_server
 Major web server products
 Apache, IIS, Nginx (a new popular one)
 Market share data
 http://w3techs.com/technologies/overview/web_server/all
 http://news.netcraft.com/
 A basic web server does not have additional processing capabilities 
 Complemented by web server extensions or modules (e.g. PHP) which add programming 
capabilities to handle advanced processing
 More specialized servers used in multi-tier web applications
 Application servers enrich and scale web applications, with features like session, transaction, 
security, etc.  see server side processing slide later.
 Database servers for data and content management
 Others: LDAP, Email, etc.
Addressing
19
 URL (Uniform Resource Locator) is used to locate a resource on a web server
 A standard in IETF RFC 1630.

http://en.wikipedia.org/wiki/Uniform_resource_locator
 The World Wide Web's naming scheme had the goal of uniquely identifying all 
objects stored on the computers on the Internet. This addressing has two parts
 Server address: identified by IP addresses or domain names

File/resource local address: identified by local address pointer
 Domain Name System (DNS)
 A system that provides the conversion between IP addresses and domain names

Top level domains are managed by ICANN (http://www.icann.org) and IANA (http://www.iana.org)
 Check IP and domain name online http://cqcounter.com/whois/
 URL types

File based URL: the URL directly corresponds to a file (either static or dynamic)
 Resource identifier based URL: the URL is only an representation (an access point) of resource 
(typically used in REST)
Extended reading: 
 https://eager.io/blog/the-history-of-the-url-path-fragment-query-auth/
 URL encoding http://en.wikipedia.org/wiki/Percent-encoding
URL (Uniform Resource Locator)
20
 URL (or web address) is used to locate a particular 
resource on a web server
 Components of a URL
 Protocol: communication language
 Host (domain, IP): web server address
 Port: application connecting point/channel
 File (resource) path and name
 Complete syntax reference: https://en.wikipedia.org/wiki/URL
 Example
http://www.spsu.edu:80/aboutus/index.htm
The default port for HTTP is 80; 
":80" is usually omitted.
"http" is the protocol for 
the Web. :// separates 
protocol and domain
"www.spsu.edu" is the domain; 
".edu" is the top level domain
"aboutus/" is the directory (path) 
on the server; "index.htm" is the 
actual file (web page). "/" is used 
for path levels.
Some URL Variations
21
 Non www domain (the server does not have to be named in www)
 http://spsu.edu/aboutus/index.htm 
 Default document (for example index.html) will be returned if the file part is 
not specified
 http://www.spsu.edu/aboutus/

If the Web (HTTP) is configured at a different port other than 80
 http://www.spsu.edu:800/aboutus/index.htm 
 URL parameter added after ?
 http://www.spsu.edu:80/aboutus/index.htm?ref=homepage
 https protocol (HTTP secured)
 https://www.spsu.edu/aboutus/index.htm 
 Virtual pointer (not an actual file)
 http://www.spsu.edu/aboutus

IP based
 http://168.12.14.112/
HTTP Overview
22
 HTTP (Hypertext Transfer Protocol) is the feature 
communication protocol for the web
 A web server and a browser communicate based on HTTP
 http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
 Features
 An application layer protocol typically running on top of TCP/IP
 A request-response cycle protocol
 Stateless - http://en.wikipedia.org/wiki/Stateless_protocol
 HTTP over TCP/IP
 HTTP is a client-server application-level protocol. 
 Typically runs over a TCP/IP connection; but it does not have 
to run on TCP/IP.
Extended reading: 
http://www.httpwatch.com/httpgallery/
HTTP Methods
23
 HTTP has two types of messages
 HTTP Request: a message sent to the web server
 HTTP Response: a message sent by the web server 
(responded by the server)
 http://www.httpwatch.com/httpgallery/introduction/
 See example HTTP request and response 
messages at http://web-sniffer.net
 Or using other tools (see the tools slide)
HTTP Request
24
 Message header
 Method (GET)
 Host
 Message body
 Contains optional data (usually used with forms)
HTTP Response
25
 Message header
 Status codes
 http://www.httpwatch.com/httpgallery/errors/
 http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
 http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
 Message body
 Actual content: HTML, etc.
Domain
26
 A domain is a name (address) assigned to a server on the 
Internet.
 A domain name is divided into several levels starting from the 
right, and separated by dots "."
 Example: 
www.spsu.edu
 Top-level domain: a highest level domain that are pre-defined; 
usually indicates the type of the site
 Created in 1980: .com, .net, .org, .edu, .gov, .int, .mil
 2 letter country code: .us, .uk, .jp, .ca, .au, .cn, 
 https://en.wikipedia.org/wiki/Generic_top-level_domain
 Generic top level domains are managed by

ICANN (http://www.icann.org) and IANA (http://www.iana.org)
"edu" is the top level domain.
"spsu" is the 2nd level domain.
"www" is the 3rd level 
domain, or host (a server).
DNS
27
 The Domain Name System (DNS) 
is a hierarchical decentralized 
naming system for computers, 
services, or other resources 
connected to the Internet or a 
private network. It associates 
various information with domain 
names assigned to each of the 
participating entities. Most 
prominently, it translates more 
readily memorized domain names 
to the numerical IP addresses.
 Address resolution mechanism
Extended reading: 
 http://en.wikipedia.org/wiki/Dom
ain_name_system
 http://computer.howstuffworks.c
om/dns.htm
Put the Simple Web Together
28
What happens after a URL is entered in the web browser?
1. Enter a URL (web address) http://spsu.edu/index.html in 
the browser. The domain will be converted to IP address 
168.28.176.243 by contacting DNS or from local cache.
2. The browser sends an 
HTTP request to the server
3. The server processes the 
request and finds the file
4. The server sends the 
result back using HTTP 
response message
5. The browser 
renders (displays) 
the file
SPSU's web server at 
168.28.176.243
Local computer 
and browser
Processing
29
 Processing capabilities enhance the Web from an 
application aspect
 At the client side
 DHTML: http://en.wikipedia.org/wiki/Dynamic_HTML
 CSS, JavaScript and various components and libraries: 
XMLHttpRequest (AJAX), JQuery, etc. 
 Browser plug-ins: Flash, Sliverlight, Java Applets, ActiveX, 
embedded objects, etc.
 At the server side
 CGI: http://en.wikipedia.org/wiki/Common_Gateway_Interface
 Web server extensions or application servers
 Major platforms: .Net (IIS, ASP.Net, Mono), Java EE (Servlets, 
JSP, EJB, WebLogic, WebSphere), PHP(Zend), Python, 
ColdFusion, etc.
Client Side Web Technology
30
 Client side technologies are supported by the web 
client (browsers)
 Everything will be downloaded to the client and executed 
by browsers
 Client side technologies
 HTML: the basic content
 Cascading Style Sheet (CSS): create web page style 
(color, size, position, etc.), layout, and simple animation
 Client-side scripting (JavaScript): advanced processing at 
the client side that provides functionalities
 Browser plug-ins
 Flash, Sliverlight, Java Applets, PDF, embedded objects, etc.
View an example at 
https://html-css-js.com
Server Side Web Technology
31
 Server side technologies are supported by web 
servers and other specialized servers
 Everything will be process on the server side before client 
side content (HTML, image, CSS, Javascript, etc.) is 
downloaded
 Server side technologies 
 Web server
 Serving static file requests
 Web server extensions or application servers
 Java, PHP, ASP.Net, Perl, CGI, ASP, ColdFusion, etc.
 Database servers
 SQL Server, MySQL, Oracle, etc.
Server Side Processing
32
Generated Content 
(HTML, CSS, etc.)
Web Server 
Extension, Module, 
or Application Server
Web Server
Client
(Browser)
Request
Response
Database 
Server
Other 
Servers: 
Email, 
LDAP, Video 
streaming, 
other web 
servers, etc.
Static files/pages
Processing 
Delegation
HTTP response message with 
client content (HTML, CSS, 
JavaScript, image, flash, etc.)
More specialized servers used 
in multi-tier web applications. 
Application servers enrich and 
scale web applications, with 
features like session, 
transaction, security, etc.
Database servers for 
data and content 
management
A basic web server does not have 
additional processing capabilities; 
it's complemented by web server 
extensions or modules which add 
programming capabilities to 
handle advanced processing.
https://developer.mozilla.org/en-US/docs/Learn/Server-side/First_steps/Introduction
Simple vs. Dynamic Web
Dynamic Web is enabled by advanced processing capabilities at both the client side and 
server side (especially the server side)
Simple/Static
Dynamic
Overview
Usually document (HTML files) based web 
applications with limited client scripting
Advanced processing is utilized at many levels
Technologies
Client side: HTML, CSS
Client side: CSS, JavaScript
Server side: PHP, Java, .Net, Python
Advantages
Simple, small and fast
Functional, versatile
Web content
Static HTML files
A mixture of HTML, scripts, programming codes, 
executable programs, data storage, etc.
Web page 
construction
Web pages are authored at design time
Web pages are "assembled" at run time (on the fly)
Content source
Single source: HTML file
Multiple sources: HTML files, XML/JSON files, other 
files, databases, other websites, etc.
Web navigation and 
interaction mode
Click and read
Rich interaction: write/type, choose, move, slide, 
drag and drop, expand, draw, listen, speak, etc.
Usage and 
Examples
Commonly used for web presence, 
information publishing, etc., for personal or 
small business websites:
http://zheng.kennesaw.edu
http://it5443.azurewebsites.net
http://www.berkshirehathaway.com
Wide range of applications: e-commerce, intranet, 
business software, e-learning, social networking, 
system admin, etc.

E-Commerce: http://amazon.com
 Web search engines: http://google.com
 Content publishing: http://wordpress.com
 Web portal: http://yahoo.com

E-Learning: https://kennesaw.view.usg.edu
Web Development
34
 Web design vs. development
 Front end, back end, full stack
 Knowledge and skills
 Development tools
 Utility tools and resources
Web Design vs. Web Development
35
 The defined lines between designers and developers are 
becoming more blurred as more designers are learning to code 
and more developers are paying close attention to design 
theory.
 http://designmodo.com/designer-vs-developer/
See the complete 
infographic at 
https://www.webfx.com/blog/
web-design/web-designers-
vs-web-developers-
infographic/
Front end vs Back end Development
36
 Front end development focuses on the client side
 User interfaces and interactions
 Applications that can be done at the client side
 Major languages: HTML/CSS/JavaScript
 Focus on usability and user experiences
 Back end development focuses on the server side
 Logic and functions
 Database operations
 Other server supported applications and services like communication, 
authentication, etc.
 Mainly use server side languages and platforms like ASP.Net/C#, 
Java, PHP, Python
 Full stack development
 Cover both front and back end, and the overall architecture spanning 
over clients and servers
Coding Tools
37
 Easy to use
 Notepad ++
 Efficient coding
 Visual Studio Code 
 https://blog.templatetoaster.com/dreamweaver-alternative-micorsoft-
visual-studio-code/
 Advanced IDE
 Visual Studio
 Eclipse
 Dreamweaver
 Web based
 http://htmleditor.tools
 https://codepen.io
 https://jsfiddle.net
Utility Tools
38
 HTTP Tools
 Browser integrated developer tools like Chrome 
Developer Tools
 Add-ons like HttpWatch https://www.httpwatch.com
 Web based like http://web-sniffer.net
 Use specific sniffing tools like WireShark
 More
 http://html-css-js.com
Web Hosting
39
 Websites and applications are put on a server to serve the 
public, which is called web hosting.
 Hosting choices
 Microsoft Azure for Students (https://imagine.microsoft.com/en-
us/Catalog/Product/99) provides free service to students. 
 GitHub Pages (https://pages.github.com) provide free services 
for Git based projects.
 Commercial hosting. Purchase your individual hosting with 
your own domain from a commercial provider
 Usually about 5 to 10 dollars per month for shared hosting
 10 to 15 dollars for a domain per year.
 Do some research using Google or 
http://www.whoishostingthis.com/hosting-reviews/
 Find a free service provider like https://www.000webhost.com
or https://www.freehosting.com
Key Readings and Resources
40
 General introduction

This lecture notes: 
https://www.edocr.com/v/qezldpd2/jgzheng
/Introduction-to-World-Wide-Web-and-
Web-Development

Introduction to Web as a Platform: 
 https://msdn.microsoft.com/library/bb3309
32.aspx
 https://www.youtube.com/watch?v=3XgEu
qKSRIw

http://www.slideshare.net/randyconnolly/ch
apter01-presentation-16514220 - the first 
chapter of the textbook Fundamentals of 
Web Development.

http://itwebtutorials.mga.edu/html/chp1/ser
ving-pages.aspx
 Server side

https://developer.mozilla.org/en-
US/docs/Learn/Common_questions/What_
is_a_web_server

https://developer.mozilla.org/en-
US/docs/Learn/Server-
side/First_steps/Introduction
 Browser

https://www.html5rocks.com/en/tutorials/internals/h
owbrowserswork/

https://hacks.mozilla.org/2017/05/quantum-up-
close-what-is-a-browser-engine/
 HTTP

http://www.httpwatch.com/httpgallery/

http://www.ntu.edu.sg/home/ehchua/programming/
webprogramming/HTTP_Basics.html
 URL

http://eager.io/blog/the-history-of-the-url-path-
fragment-query-auth/
 DNS

http://computer.howstuffworks.com/dns.htm

http://en.wikipedia.org/wiki/Domain_name_system
 Development

https://www.w3schools.com

https://www.codecademy.com

https://developer.mozilla.org

http://www.w3resource.com

http://html.net

https://html-css-js.com