If you're a more advanced user, you've probably downloaded and installed Mozilla Firefox for your Web browsing convenience and safety.
One of the drawbacks to the main competitor, Microsoft's Internet Explorer, is that Internet Explorer is a Microsoft product and therefore only open to what people at Microsoft deem important. This sort of cripples innovation on some level. If you're a young software engineer at Microsoft with a great idea, it might get pushed off in favor of more pressing issues.
Firefox is an open-source program, which in part means that anyone with some computer programming ability can create a program to do things and contribute it to the project. Some of these are incorporated directly in the program; others are known by other names such as plug-ins, add-ons, or extensions.
My favorite add-on has to be one called Foxmarks. Basically, what are called "Favorites" in Internet Explorer are called "Bookmarks" in Firefox. This program will synchronize your bookmarks. In other words, instead of having different bookmarks on your home computer, work computer, and other computers you might use, Foxmarks will let you have the same bookmarks on all the machines that you use. It does require the software to be installed on each machine, but once it's set up, it makes life just so much easier.
The best part? Like the Firefox browser and most add-ons, it's free.