Types of humour

Here are some of the most typical kinds of jokes:

a put-down
a pun
offbeat humour
an epigram
black humour
a stock joke

And  here is a link to The Devil's Dictionary by Ambrose Bierce , where words are defined in a different way:

DENTIST, n. A prestidigitator who, putting metal into your mouth, pulls coins out of your pocket.
POLITICS, n. A strife of interests masquerading as a contest of principles. The conduct of public affairs for private advantage.
FAITH, n. Belief without evidence in what is told by one who speaks without knowledge, of things without parallel.

If you want to listen to jokes in English:
 
http://www.manythings.org/jokes/ (quite easy, though)

http://www.dailycomedy.com/jokes/mp3