Frames have long been a source of debate in terms of good web design. They are the commonest e-mail request in terms of composer we get, hence this expanded section.
If you didn't know already frames essentially allow you to display two or more webpages within one browser window (click the link at the top to see this page is an example of a frame). If that doesn't make much sense consider the example below
header
side menu
Main AREA
This page is made up of 3 webpages. You have the the header page, the side menu page and the main area page. The advantage with frames is that you could create a link within any of these 3 frames that would change the main area frame
e.g.
header
side menu
Main Area
header
side menu
New Page
thereby giving consistency to your page with menu and header
Frames are not universally popular. Whilst the vast bulk of surfers are indifferent, there are 2 vocal, (very) minority camps with opposing views. Several criticisms cann be laid at the doors of frames. Firstly frames can suffer badly from screen resolution. Secondly not all browsers support them. Frames can be a nightmare to create links in. Remember each page making up a frame set needs to load in (hence can mean lengthy download times). Finally often can create horrible looking pages (as their oppostion frequently point out).
Composer doesn't directly support frames but there are ways round this.