The PRE tag is used for text that has to be formatted in a certain way. When using the PRE tag P or BR is not needed to start a line, you just hit enter when writing the text. By pressing enter many times you get whitespace. You can even use tabs within PRE. Images can't be used inside this tag, because a graphic can't be converted into a certain amount of characters. The optional WIDTH attribute is used to tell how wide the text is, but it isn't widely supported.
<PRE> This text was made using the PRE tag.</PRE>
This text was made using the PRE tag.