Rake
Rake is the amount or maintenance fee the casino or online poker room charges for letting you play poker at their tables. Compared to other popular casino games like the roulette or blackjack poker is the only casino game where you do NOT play directly against the casino but against other poker players.
In other casino games the casino earn their money due to the statistical house edge the have meaning that they will always win in the long run but as this does not exist in poker the poker room or casino charges a rake on all poker games.
The rake is charged differently depending on the game. In tournaments the rake is a fixed fee (also called tournament fee) and it is very simple to recognize what you are paying to play the tournament. For example in a 200$+20$ tournament the 200$ goes toward the total price pool and the 20$ is the fee / rake you pay to the casino or poker room to play the tournament.
In cash games it is a little bit more complicated as the rake is charged on the total pot of every hand played. Normally the rake charged is between 5 and 10% with a maximum of 3$/€ per hand.
For example if you win 10$ in a cash game you will have to pay between 0,5$/€ and 1 $/€ in rake.
Although it is the winner of the hand that actually pays the rake he is not the only player that have put in money to the pot and therefore when calculating how much rake you have paid you have to take this into consideration.
There are different ways whereby the rake each player have paid is calculated. The two most comon ways is either by the percentage of money you have put into the pot (if you have put in 2$/€ into a 10$/€ pot although you loose 20% of the rake paid comes from your account) or dividing equally between all players that have contributed with money to the pot.