I have been using Firefox browser from Mozilla from sometime. It beats Microsoft Internet Explorer (IE) on many counts and I feel this is the best browser available today. It is free and its open source!
To download later version of Firefox visit this link http://www.mozilla.com/firefox/ 

Some of the features of Firefox which I liked are:

1. Tabbed Browsing: This is a very good feature which doesn’t exist in IE. Using this feature one can open links in a new tab in the same window instead of opening links in new window. The pages which we visit become more manageable because of tabbed browsing. This feature is very useful when one is searching for some specific information on google and you need to open many search result pages to find his answer. Different search result can be opened in the same window in different tabs.
2. Indexed searching: This is the feature which I like most in Firefox.  I used to find it very difficult to search for some specific word on the web page that I had opened using IE. In IE I had to go to the beginning of the page, press Ctrl+F & then search. IE would then start the search. It was a very cumbersome approach. With Firefox searching on a page is very simple. When a page is opened using firefox, firefox indexes all the words in that page. When one presses Ctrl+F and starts typing for the required word firefox starts searching (even before you click on the ‘Find’ button!!). It highlights the search result with Green color. And if the word which one is searching for is not present, the seach text box immediately becomes red without a need for pressing the ‘Find’ button! Try this feature it’s really amazing!
3. Integrated search: One can search for keywords on various search engines without visiting their page because at the top right corner of the firefox browser window there is an option to enter keyword and to search from various search engines.
4. Better auto suggest in the address bar: The auto suggest of url as you type a new url on the browser address bar is much better than IE. IE doesn’t rank the previously visited url properly & it always gives me wrong suggestions. Firefox has got a good ranking system of urls in the address bar and it always suggests me the most likely url.
5. Better Security: This is the single biggest reason which made Firefox very famous. IE has got lot of security holes. Firefox has much lesser security holes and is more secure than IE. At my home I was using IE and my computer got infected with lots of spywares, worms & viruses, ultimately my computer because un-usable.. I had to re-format my hard disk. When I talked to my friend Arjun on this problem, he said that even he had faced similar problems and he switched over to firefox and his problems got solved! So, even I switched over to firefox.
6. Improved Pop-up blocking: It has got a advanced pop up blocking mechanism to block annoying popups, [which pop up every now and then ]
7. Miscellaneous: When I used to visit the famous social networking site orkut using IE, every time the site used to ask me to login. This used to happen even though I used to check the ‘Remember me on this computer’ option. This was very annoying. After I switched over to firefox this problem dissapeared!
8. It has many many other features which are great! Just start using and you’ll know.

Google is providing lot of support to Firefox [to beat Microsoft ]. To get google extensions for firefox, check out http://toolbar.google.com/firefox/extensions/

So what are you waiting for? Start using firefox and I bet you’ll get hooked on to it!