Programs used to view documents on the Web. Netscape Navigator and Microsoft Internet Explorer are the most popular browsers today. Mosaic was the first big one that made the Web popular. It is now an historical artifact. Plug-ins or viewers make multimedia viewing or listening possible.
Browsers have several built-in.
You will no doubt have to add some over time. Popular ones are Acrobat and RealPlayer. Your personal page or your default starting page on the Web. Portals, Hubs, and Home Bases. Aggregations of interconnected web sites that people link up to depending on their interests.