A web browser is a software application for finding, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier (URI) and can be a web page, image, video, or other piece of content.1 Hyperlinks in resources allow users to easily navigate their browsers to related resources. .

The main purpose of a web browser is to bring information resources to the user. This process begins when the user enters a Uniform Resource Identifier (URI) for http://en.wikipedia.org/ for example, in the browser. The URI prefix determines how the URI will be interpreted. The most commonly used URI type begins with http: and identifies a resource to be retrieved over the Hypertext Transfer Protocol (HTTP). Many browsers also support a variety of other prefixes, such as https: for HTTPS, http: or File Transfer Protocol, and file: for local files. Prefixes that the web browser cannot handle directly are often handed off to another application entirely. For example, mailto: application URIs are usually forwarded to the user's default email and news: URIs are forwarded to the user's default news reader.

In the case of HTTP, HTTPS, file, and others, once downloaded the resources the web browser will display. HTML is passed to the browser engine layout to be transformed from an interactive bookmark document. In addition to HTML, web browsers can generally display any content that may be part of a web page. Most browsers can display images, audio, video, and XML files, and often have plug-ins to support Flash applications and Java applets. When faced with an unsupported file or a file that is configured to be downloaded rather than displayed, the browser prompts the user to save the file to disk.

Interactivity in a web page can also be provided by Javascript, which usually does not require a plug-in. Javascript can be used in conjunction with other technologies to allow "live" interaction with the web page server via AJAX.

information resources may contain hyperlinks to other information resources. Each link contains the URI of a resource to go to. When a link is clicked, the browser navigates to the resource indicated by the target URI link, and in the process of creating content for the user begins again

Although browsers are primarily intended to access the World Wide Web, they can also be used to access information provided by Web servers on private networks or files in file systems. Some browsers can also be used to save information resources for file systems.

Most browsers support HTTP Secure and provide quick and easy ways to clear web cache, cookies, and browsing history. For a comparison of current browser security vulnerabilities, see Comparison of Web Browsers.

Early Web browsers only supported a very simple HTML version. The rapid development of web browsers has led to the development of non-standard HTML dialects, leading to interoperability issues. Modern web browsers support a combination of standards-based and de facto HTML and XHTML, which should become the same for all browsers.

(most popular browsers: Mozilla Firefox, Google Chrome, Internet Explorer, Opera, Safari)