These frames can work independently of one another. You can keep navigation menus static while other areas of the page change.
Frames have several big disadvantages, however.
Frames often pose navigation problems. Frames often cause problems in bookmarking a specific page. Frames often cause problems in printing a page. Many users become confused when trying to print a page in a frameset because they will often print the content of another frame on the page. At BU WebCentral, we have determined that the disadvantages of frames outweigh the advantages.