Web browser

A web browser (commonly referred to as a browser) is application software for accessing the World Wide Web. When a user requests a

web page

from a particular

website

, the web browser retrieves the necessary content from a web server and then displays the page on the user's device.

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. However, to connect to a website's server and display its web pages, a user must have a web browser installed.

Web browsers are used on a range of devices, including desktops,

laptop

s, tablets, and

smartphone

s. In 2020, an estimated 4.9 billion people used a browser. The

most used

browser is

Google Chrome

, with a 65% global market share on all devices, followed by Safari with 18%.

Function

The purpose of a web browser is to fetch content from the Web and display it on a user's device.

This process begins when the user inputs a

Uniform Resource Locator

(URL), such as ''https://en.wikipedia.org/'', 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 (HTTP). In the case of secure mode (HTTPS), the communication between the browser and the web server is

encrypted

for the purposes of security and privacy.

Once a

web page

has been retrieved, the browser's rendering engine displays it on the user's device. This includes

image

and

video

formats supported by the browser.

Web pages usually contain

hyperlink

s to other pages and resources. Each link contains a URL, and when it is clicked or

tapped

, the browser navigates to the new resource. Thus the process of bringing content to the user begins again.

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.

Settings

Web browsers can typically be configured with a built-in menu. Depending on the browser, the menu may be named ''Settings'', ''Options'', or ''Preferences''.

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

font

s. Various network connectivity and privacy settings are also usually available.

Privacy

During the course of browsing, cookies received from various

website

s are stored by the browser. Some of them contain login credentials or site preferences. However, others are used for tracking user behavior over long periods of time, so browsers typically provide a section in the menu for deleting cookies. Finer-grained management of cookies usually requires a browser extension.

Browsers also usually provide menu items for deleting browsing history, cache entries, and other potentially sensitive data.

An alternative approach is the private browsing mode, in which the aforementioned items are not stored by the browser. But this is a temporary option, only activated when using this special mode.

Features

The most popular browsers have a number of features in common. They automatically log browsing history or can be used in a non-logging private mode. They also allow users to set bookmarks, customize the browser with extensions, and can manage user

password

s. Some provide a sync service and web accessibility features.

Most browsers have these user interface (UI) features:
* Allow the user to open multiple

pages

at the same time, either in different browser windows or in different tabs of the same window.
* ''Back'' and ''forward'' buttons to go back to the previous page visited or forward to the next one.
* A ''refresh'' or ''reload'' and a ''stop'' button to reload and cancel loading the current page. (In most browsers, the stop button is merged with the reload button.)
* A ''home'' button to return to the user's

home page

.
* An address bar to input the

URL

of a page and display it.
* A search bar to input terms into a search engine. (In some browsers, the search bar is merged with the address bar.)

While

mobile browser

s have similar UI features as desktop versions, the limitations of

touchscreen

s require mobile UIs to be simpler. The difference is significant for users accustomed to keyboard shortcuts. The most popular desktop browsers also have sophisticated web development tools.

Besides the common usage of graphical browsers, there are niche text-based and headless types of browsers.

Security

Web browsers are popular targets for

hacker

s, who exploit security holes to steal information, destroy files, and other

malicious

activities. Browser vendors regularly patch these security holes, so users are strongly encouraged to keep their browser software updated. Other protection measures are antivirus software and avoiding known-malicious

website

s.

History

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.

1993 was a landmark year with the release of Mosaic, credited as "the world's first popular browser". Its innovative graphical user 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. Within a few years, Microsoft gained a dominant position in the browser market for two reasons: it bundled Internet Explorer with its popular Windows