A lot of people will think that google uses meta tags
<meta name="description" content="this is kool 'eh">
Google willl actually search the page for keywords it self then decide how to list them.
Now you are probably wondering how does google decide who is at the top and who is at the bottom. Two Ways:
1) Relavancy - If it has you listed under Pizza then pizza would be the big topic on that page
2) Linkage - The amount of links going to that page from external sources.
Hope this helps. I know it did when i had a website :P