There are many browser products available, and each browser product has different features. The two most popular windowing-based browsers are Netscape and Internet Explorer. While we won't describe all the features of web browsers, they have a common basic set:
All web browsers are HTTP clients that send requests and display responses from web servers (usually in a graphical environment).
All browsers interpret pages marked up with HTML when rendering a page; that is, they present the headings, images, hypertext links, and so on to the user.
Some browsers display images, play movies and sounds, and render other types of objects.
<form>or change how a page is presented based on user actions.
Selected web browsers can run components developed in the Java or ActiveX programming languages. These components often provide additional animation, tools that can't be implemented in HTML, or other, more complex features.
Several browsers can apply Cascading Style Sheets (CSS) to HTML pages to control the presentation of HTML elements.
Web browsers are the most obvious example of a user agent, a software client that requests resources from a web server. Other user agents include web spiders-automated software that crawls the Web and retrieves web pages-and proxy caches, software systems that retrieve and locally store web pages on behalf of many other user agents.