The Line Break element specifies that a new line must be started at the given point. The amount of line space used is dependant on the particular browser, but is generally the same as it would use when wrapping a paragraph of text over multiple lines.
Example of use:
<P>
Mary had a little lamb<BR>
It's fleece was white as snow<BR>
Everywhere that Mary went<BR>
She was followed by a little lamb.
With the addition of floating images (I.e. the ability to align an embedded image to the left or right of the browser display window) it became necessary to expand the <BR> element. Normal <BR> still just inserts a line break. A CLEAR attribute was added to <BR>, so :
CLEAR=left will break the line, and move vertically down until you have a clear left margin (I.e. where there are no floating images).
CLEAR=right does the same for the right margin.
CLEAR=all moves down until both margins are clear of images.
NOTE : The CLEAR attribute (as well as floating images) are currently only supported by Netscape and the Internet Explorer.