This article is from the Go FAQ, by Morten PAHLE firstname.lastname@example.org with numerous contributions by others.
Go tournaments are often a good opportunity to meet other players who
do not always come to the club, and players from out of town.
Furthermore, there is usually enough time after and between matches to
replay, discuss or play more. All in all, in a tournament which runs
over a weekend, you can expect to play more games than the number of
rounds would indicate.
Even without knowing the details of how tournaments are organised, you
will have a lot of fun.
A good tournament system enables the ranking of a large class of
players (say 15-20) with relatively few rounds (typically 4-5).
Several ways of organising tournaments exist. Various systems are
described by Robert JASIEK in his Rules FAQ.
You can also take a look on Ken's pages: