Begin a new line under the startpoint of the current line. Use <BR CLEAR> to make the line start in the left or right margin, if you e.g. have a picture on the side of the text. Use CLEAR=ALL if you have pictures on both side of the text.
<NOBR>
Stands for 'No Break'. Use it if you want the text inside the tag to appears on the same line. Don't forget to end with </NOBR>.
<WBR>
Stands for 'word break'. Starts a new line if the browser need to. Use it, for example, inside a long word.
<P [ALIGN=LEFT|RIGHT|CENTER|JUSTIFY] [NAME=text]>
Stands for 'paragraph'. Use it to start a new paragraph. Use ALIGN to start the line in the left, right or center part of the page. Justify makes straight margins. NAME is optional, and used as an anchor. Please read the Links chapter for more. <P> can end with </P>, but it's optional. Most of the parameters are HTML 3.0 tags.
<CENTER>
Use it to center text and pictures. Netscape tag, but well supported. Must end with </CENTER>.
<DIV ALIGN="left|center|right">
Aligns text, pictures and other contents together. Netscape 2.0 tag. I think it must end with </DIV>.