TVTropes to the rescue!
-san
The most common honorific, and the one most familiar to non-Japanese. Roughly equivalent to almost all everyday English honorifics, it is generally employed with someone of the same social station as yourself, but can be used any time you need to be generically polite. This is commonly translated as 'mister' or 'ms'.
...I had TVTropes open so it was the easiest way for me to explain things. :(