what is frame set? Its not clearly described in solo learn

Answer 1

The <frameset> tag defines a frameset.

The <frameset> element holds one or more <frame> elements. Each <frame> element can hold a separate document.

The <frameset> element specifies HOW MANY columns or rows there will be in the frameset, and HOW MUCH percentage/pixels of space will occupy each of them.

Answer 2

Frameset is all about frames, but, with frameset you can put a lot of them and setup their style.

Example:

<frameset cols="25%,*,25%">
<frame src="frame_a.htm">
<frame src="frame_b.htm">
<frame src="frame_c.htm">
</frameset>

Be careful: frameset is not supported in HTML5