Web browser

A web browser, often shortened to browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers can also display content stored locally on the user's device.

Browsers are used on a range of devices, including desktops, laptops, tablets, smartphones, smartwatches and consoles. As of 2024^[update], the most used browsers worldwide are Google Chrome (~66% market share), Safari (~16%), Edge (~6%), Firefox (~3%), Samsung Internet (~2%), and Opera (~2%). As of 2023, an estimated 5.4 billion people had used a browser.

The purpose of a web browser is to fetch content and display it on the user's device. This process begins when the user inputs a Uniform Resource Locator (URL), such as https://en.wikipedia.org/, into the browser's address bar. Virtually all URLs on the Web start with either http: or https: which means they are retrieved with the Hypertext Transfer Protocol (HTTP). For secure mode (HTTPS), the connection between the browser and web server is encrypted, providing a secure and private data transfer. For this reason, a web browser is often referred to as an HTTP client or a user agent. Requisite materials, including text, style sheets, images, and other types of multimedia, are downloaded from the server. Once the materials have been downloaded, the web browser's engine (also known as a layout engine or rendering engine) is responsible for converting those resources into an interactive visual representation of the page on the user's device. Modern web browsers also contain separate JavaScript engines which enable more complex interactive applications inside the browser. A web browser that does not render a graphical user interface is known as a headless browser.

Web pages usually contain hyperlinks to other pages and resources. Each link contains a URL, and when it is clicked or tapped, the browser navigates to the new resource. Most browsers use an internal cache of web page resources to improve loading times for subsequent visits to the same page. The cache can store many items, such as large images, so they do not need to be downloaded from the server again. Cached items are usually only stored for as long as the web server stipulates in its HTTP response messages.

A web browser is not the same thing as a search engine, though the two are often confused. A search engine is a website that provides links to other websites and allows users to search for specific resources using a textual query. However, web browsers are often used to access search engines, and most modern browsers allow users to access a default search engine directly by typing a query into the address bar.

The first web browser, called WorldWideWeb, was created in 1990 by Sir Tim Berners-Lee. He then recruited Nicola Pellow to write the Line Mode Browser, which displayed web pages on dumb terminals. The Mosaic web browser was released in April 1993, and was later credited as the first web browser to find mainstream popularity. Its innovative graphical user interface made the World Wide Web easy to navigate 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. The lead developers of Mosaic then founded the Netscape corporation, 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. Within a few years, Microsoft gained a dominant position in the browser market for two reasons: it bundled Internet Explorer with its popular Windows operating system and did so as freeware with no restrictions on usage. The market share of Internet Explorer peaked at over 95% in the early 2000s. In 1998, Netscape launched what would become the Mozilla Foundation to create a new browser using the open-source software model. This work evolved into the Firefox browser, first released by Mozilla in 2004. Firefox's market share peaked at 32% in 2010. Apple released its Safari browser in 2003; it remains the dominant browser on Apple devices, though it did not become popular elsewhere.

Google debuted its Chrome browser in 2008, which steadily took market share from Internet Explorer and became the most popular browser in 2012. Chrome has remained dominant ever since. In 2015, Microsoft replaced Internet Explorer with Edge [Legacy] for the Windows 10 release. In 2020, this legacy version was replaced by a new Chromium-based version of Edge.