Serach Engines

I decided to check the possibility of making a search engine. I really dont understand the concept behind a search engine that searches for keywords. So once again, I put together a poster explaining my findings. Here are the links shown on the poster
http://dev.mysql.com/doc/refman/5.0/en/fulltext-boolean.html

http://www.intechgrity.com/how-to-connect-to-xamppmysql-using/