A web browser (commonly referred to as a browser) is a software application for accessing information on the World Wide Web. Each individual web page, image, and video is identified by a distinct URL (URL), enabling browsers to retrieve these resources from a web server and display them on the user's device.
The web browser works as follows." A Survey of Techniques for Improving Efficiency of Mobile Web Browsing", Mittal et al., Concurrency and Computation, 2019 First, the rendering engine parses CSS and HTML files. While parsing the HTML file, the rendering engine also produces DOM tree data construct where every node refers to an HTML tag, a property or a section of a text. CSS decides the visual style of the webpage based on the style rules, each of which selects single/multiple HTML tags for applying the properties. During parsing, CSS rules are extracted and corresponding data structure is constructed. Based on CSS rules and DOM tree, the style resolution unit decides the style information of the page (such as color font) by generating the render tree. Every node of the render tree corresponds to one visual component of the webpage. From this, the layout unit computes the precise screen-coordinates of every visual component. Finally, the painting unit traverses the render tree and invokes graphics library to actually display the page on the screen.
A web browser is not the same thing as a search engine, though the two are often confused. For a user, a search engine is just a website, such as Google Search, that stores searchable data about other websites. But to connect to a website's server and display its web pages, a user needs to have a web browser installed on their device.
As of March 2019, more than 4.3 billion people are web browser users, around 55% of the world’s population. Their success is in part caused by their flexibility, due to their Turing-complete execution and powerful graphic capabilities.
1993 was a landmark year with the release of Mosaic, credited as "the world's first popular browser". Its innovative graphical interface made the World Wide Web system easy to use and thus more accessible to the average person. This, in turn, sparked the Internet boom of the 1990s when the Web grew at a very rapid rate. Marc Andreessen, the leader of the Mosaic team, soon started his own company, Netscape, which released the Mosaic-influenced Netscape Navigator in 1994. Navigator quickly became the most popular browser.
Microsoft debuted Internet Explorer in 1995, leading to a browser war with Netscape. Microsoft was able to gain a dominant position for two reasons: it bundled Internet Explorer with its popular Microsoft Windows operating system and did so as freeware with no restrictions on usage. Eventually the market share of Internet Explorer peaked at over 95% in 2002.
In 1998, desperate to remain competitive, Netscape launched what would become the Mozilla Foundation to create a new browser using the open source software model. This work evolved into Firefox, first released by Mozilla in 2004. Firefox reached a 28% market share in 2011.
The last major entrant to the browser market was Google. Its Google Chrome browser, which debuted in 2008, has been a huge success. It steadily took market share from Internet Explorer and became the most popular browser in 2012. Chrome has remained dominant ever since.
This process begins when the user inputs a URL, such as <nowiki></nowiki>, into the browser. Virtually all URLs on the Web start with either http: or https: which means the browser will retrieve them with the Hypertext Transfer Protocol. In the case of https:, the communication between the browser and the web server is HTTPS for the purposes of security and privacy. Another URL prefix is file: which is used to display computer file already stored on the user's device.
Web pages usually contain to other pages and resources. Each link contains a URL, and when it is clicked, the browser navigates to the new resource. Thus the process of bringing content to the user begins again.
The menu has different types of settings. For example, users can change their home page and default search engine. They also can change default web page colors and . Various network connectivity and privacy settings are also usually available.
Most browsers have these user interface features:
There are also niche browsers with distinct features. One example is text-only browsers that can benefit people with slow Internet connections or those with visual impairments.
Certain browser Software feature contain commonly exploited vulnerabilities. They include:
Methods used to secure web browsers and computers in general include keeping browser software updated, installing and using antivirus software, and avoiding malicious content and website-based exploits.