What does a web browser do?

What does a web browser do?

By Tharindu Weerasinghe [MSc.Eng, BSc.Eng(Hons)]

In the contemporary society, with the various technological influences, even a 3 year old kid would know the term “Web Browser”. Due to the fact that internet is pretty closed to many families, children know that they need a web browser to surf internet. But most of them and also most of the general public are not aware of the functions of a web browser beyond the fact that it shows us web pages that are requested by us.  This article will give a simple overview of web browsers. But please note that there are many complex aspects web browsers when it comes to completing its main objectives.

Web browser is a software application that enables retrieving, presenting and traversing information in the internet as well as in web servers that host web based software applications via private networks. These browsers are sometime called as clients as they act a client or interface between the user (you and me) and backend (server side).

Famous web browsers are:

·         Internet Explorer for Windows

·         Safari for Mac

·         Opera, Google Chrome and Mozilla Firefox for many platforms and also there are many others too….

Brief History:

The very first web browser was created by Sir Tim Berners-Lee in 1990. It was then called Worldwide Web and later renamed Nexus. In 1993, web browser technology was innovated by Marc Andreessen with the release of Mosaic (later Netscape), "the world's first popular browser", which made the World Wide Web system easy to use and more accessible to the average person. Andreessen’s browser sparked the internet boom of the 1990s but the introduction of Mosaic in 1993 allowed the world to experience one of the first graphical web browsers which led to an explosion in web use (Reference/Source: Wikipedia)

Function in brief:

A web browser preliminary knows the language, i.e. HTTP (Hyper Text Transfer Protocol). That means a web browser sends and retrieves data (communicate) by using the above protocol. Most of the modern browsers know protocols like HTTPS (Hyper Text Transfer Protocol Secure), FTP (File Transfer Protocol).

Objectives of a browser in a nutshell:

Ø  Retrieval of information upon the request by the user

Ø  Rendering the information retrieved. (Allow the users to view the information)

Ø  Access other information (When users clicks on other links)

So, the function starts with user giving the needed URL. What is a URL? It stands for Uniform Resource Locator, which is most commonly known as the web address.

Example URL is http://www.dailynews.lk/2013/02/21/main_News.asp

·         The prefix of the URL or the first set of strings stands before the colon mark (:), is called the Uniform Resource Identifier or URI, that determines how the URL will be interpreted i.e. what is the protocol that should be used for communication (when it comes to the term communication, a web browser always act as communication interface between the user and the server which are located in two different places, So this communication is called the client-server communication). In the above example, it is Hypertext Transfer Protocol (HTTP) which is the most common protocol.

·         Browser will send the request to the relevant server which host the web page and then retrieve it. If it is a LAN (Local Area Network) of an organization or institution then most probably they have proxy server before their network is exposed to the outer world (i.e. Internet), So, in those cases the request sent by the browser is accepted by the proxy server (which should be already configured in the browser) and if the proxy server has the particular web page in its cache then it shows it.

·         So, after having retrieved the information (which are HTML – Hyper Text Markup Language) and other associated content (image files, formatting information such as CSS, etc.), those information are sent to the browser’s layout engine (which is in-built with the browser) to transform them into a readable and visible information. This process is called “rendering”.

o   What is a web browser engine? (or layout engine/rendering engine)

A web browser engine, is a software implementation (normally built-in with the browser) which absorbs marked up content (e.g. HTML, XML, image files, etc.) and formatting information (e.g. CSS, XSL, etc.) and displays the formatted content where the user can read and visualize the information in a lucid and palatable way.

This engine is embedded not only in web browsers but also in e-mail clients, e-book readers or other applications that need the displaying (and editing) of web content. Typically engines may wait till all data are received before rendering a page, or may begin rendering before all data is received. That differs with the engine design technology.

Browser engines of famous web browsers:

Trident - Microsoft Internet Explorer

Gecko - Mozilla Firefox

Presto – Opera

By Tharindu Weerasinghe [MSc.Eng, BSc.Eng(Hons)]