Tables are a very good way to divide a document and control the relative placement of text and other objects.
Molecules
chemical formula
CH4O
C2H6O
C6H12O6
common name
methanol
ethanol
glucose
<DIV> and <SPAN> These tags are invisible to the viewer, but serve the useful purpose of giving the document logical structure.
If you can read this your browser doesn't know about fonts
The id tag lets an anchor tag <A> go to this location as in:
Hit here for a paragraph in martian.
Hit here for a poisonous molecule.
<span> is similar but acts like a author-defined style.
If you can read this your browser doesn't know about fonts
<p>If you can read this <span style="color:green">your </span> browser doesn't know about fonts</p>