The suffix -chan is a term of endearment, usually used amongst girls. The suffix -kun (not -kunt) is another affectionate term, usually used among friends, especially boys. The suffix -san is most closely equated with "Mr." or "Ms.".

Things you may also hear in manga and anime are -sama, which is for people of high rank like a lord or a king (or God, as the term Kami-sama implies). The suffix -dono is extremely respectful, and you rarely hear it outside of Rurouni Kenshin. It actually means "lord", in this case, but -sama is more often used in the case of a king.

If you have manga, you'll note that a lot of them, especially those published by Del Ray, have notes in the front or back of the book explaining this.