History of the Internet

Internet History

• The Internet originated from ARPANET (Advanced Research Projects Agency Network).
• ARPANET was launched in 1969 by the U.S. ARPA to network the main computer systems of a dozen ARPA-funded universities and research institutions.
• By the end of 1969, ARPANET connected four computers located at UCLA, Stanford Research Institute, University of California Santa Barbara, and the University of Utah.
• In 1972, email on ARPANET became popular.
• Networks like NSFnet were created and connected with ARPANET.
• The Internet was originally limited to government, research, and educational purposes.
• There were over 100,000 hosts on the internet by 1989.
• The ban on commercial use was lifted in 1991.
• There were over 1 million hosts connected by the end of 1992.

What is the Internet?

• The Internet is a collection of computers connected in a communication network.
• In 1974, TCP/IP with IPv4 protocol was designed by Bob Kahn and Vint Cerf.
• TCP/IP has been adopted as the official communication protocol.
• The TCP/IP became the standard for computer network connections in 1982.
• The Internet is a network of networks as opposed to just a network of computers.
• All devices connected to the internet must be uniquely identifiable using an IP address.

World Wide Web History

• In 1989, Tim Berners-Lee began to develop a technology for sharing information via hyperlinked text documents.
• He proposed the basic elements of the web.
• The client he created was the first client browser "WorldWideWeb," which was also a web editor.
• The server he created was the first web server “httpd”.
• Other key elements initiated are the Uniform Resource Locator (URL), Hypertext Transfer Protocol (HTTP), and HyperText Markup Language (HTML).
• In 1991, the source code was posted on the internet which attracted users to web technology.
• In 1993, Mosaic, the first graphics-based web browser, became available.
• In October 1994, Tim Berners-Lee founded the World Wide Web Consortium W3C to oversee protocol and standards development.

Basic Elements of the Web

• An IP address is the address of a machine connected to the internet and a unique 32-bit number.
• IP addresses are written as four octets of 8-bit numbers separated by dots.
• For example, the IP address for United Airlines is 209.87.113.93
• Domain Names are text-based names introduced to solve the problem where IP addresses are difficult for users to remember.
• A URL stands for Uniform Resource Locator.
• With a URL, you identify the network resources on the Internet.
• Example of URL: https://www.hostinger.com/tutorials/what-is-a-domain-name
• Documents provided by servers on the web are requested by browsers.
• Browsers, programs running on client servers, allow users to browse server resources.
• Mosaic was the first browser with a graphical user interface.

Web Client and Server Defined

• A web client is software that accesses a web server via an HTTP request message
• Web browsers running on desktop or laptop computers are the common web client software.
• A web server is a computer program that delivers content like web pages using HTTP over the World Wide Web.
• A web server's primary function is to accept HTTP requests from web clients and return an appropriate resource in the HTTP response.

Related Terms

• Web Pages: Documents containing text and graphics created with HTML. They're part of hypertext documents accessible via web browsers, such as “index.html”.
• Web Sites: Collections of related web pages at a single address, where a URL serves as the top-level address. For example, http://www.google.com.
• Web Applications: Sets of web pages generated in response to user requests. Examples include online stores like Shopee, auctions, news sites, and games.

Static Web Pages

• Stored as HTML documents that do not change in response to user input and have filenames with the .htm or .html extension.
• Process: a web browser requests a web page by entering its address or clicking a link, it sends an HTTP request to the website's server and the web server retrieves the requested HTML file and sends it back to the browser.

Dynamic Web Pages

• Change based on parameters sent to the web application from another page.
• The web application generates the HTML for a new web page and sends it back to the browser.
• A search engine is an example.

Core Components of Web Applications

• User Interface (UI) includes front-end applications and frameworks.
• Request Layer processes Web API requests.
• Back End handles Databases and Logic.
• Client includes the web browser.

Front-End/Client-Side Languages

• HTML/CSS
• Javascript
• Java (applets)

DOM (Document Object Model)

• DOM makes every addressable item in a web application an Object that can be manipulated.

Client Side vs Server Side Scripting

• Client Side: Used to develop the front-end of the product, seen and interacted with by users, usually has faster response time.
• Server Side: Focuses on the core functionality of the product, hidden from end-users, offers customizable responses based on user requirements and has languages like PHP, Python, ASP.NET.

About Client Side and Server Side Scripting

• Client-side scripts have greater access to the information and functions available on the user's browser.
• Server-side scripts have greater access to the information and functions available on the web server.
• Server-side scripts require an interpreter installed on the server.
• Client-side scripts do not require additional software on the server, but the web browser of the user must understand the chosen scripting language.

Web Framework

• Web frameworks support the development of dynamic websites, web applications, and web services.
• They provide prewritten code and libraries with functionality common to a class of applications forming a base or skeleton.

Relation Between Framework and Library

• A library is a collection of reusable functions used by computer programs, while a framework is a piece of code that dictates the project's architecture.
• Libraries allow programmers to choose where and when to insert or use the library but a framework dictates where to put a specific part of the user's code.
• Libraries are more flexible than frameworks which have enforced structures and standards.
• React.js and jQuery are javascript libraries
• Angular JS and Vue JS are javascript frameworks.