In HTML, a frameset is a group of named frames to which web pages and media can be directed; an iframe provides for a frame to be placed inside the body of a document.
Since the early 2000s, the use of framesets has increasingly been considered obsolete due to usability and accessibility concerns, and the feature has been removed from the HTML5 standard.
The HTML 4.0 standard included two different forms of frame,
frame element, used inside a special
frameset container, and the
iframe element, used within the body of a document.
In HTML 4.01, a document, which would normally contain a
head and a
body, may instead contain a
head and a
frameset (but not both a
body and a
frameset). The attributes
cols on the opening
frameset tag define the dimensions of a grid of frames using comma-separated lists of sizes, specified in either pixels or percentages. Any row or column size may be replaced with an asterisk to indicate the remainder of the remaining screen space. Within the
frameset, a series of
frame elements describe the initial source documents for each frame in the frameset, as well as assigning them names for use as the target of links. The
<noframes> element may be included so web browsers with frames disabled (or browsers that do not support frames) can display something to the user, as in this example:
iframe element is used inline within a normal HTML body, and defines the initial content and name similarly to the