For instance, one familiar frameset includes a page split into three frames. Frame 1, at the top of the page, contains a header, such as a company logo. This frame usually never changes and maintains a consistent visual design. Frame 2, usually on the left, contains the table of contents for the Web site. For each item listed in the table of contents, a link has been set to the page related to that item. Frame 3, on the right, contains the content page for the Web site. If you click an item in the table of contents in Frame 2, the page of the link destination is displayed in Frame 3.
When you use frames, the frameset page serves as the top page for your site. Therefore, if your provider requires that a top page have the name index.html, assign that name to your frameset page.