Definition of fee
The "fee" is an English word meaning "fresh". Fees as in "entrance fee". Even if we literally translate fee as fees, the word used in French is "commission". The other English expression used is rake (the scratch). All forms of poker have their fees that the house takes. If you are a tournament player, for example, you will see a tournament advertised as follows: 10+1. You then know that 10 euros will go into the main prize pool and 1 euro will go to the house (at the casino or online gambling room) as a fee.
fee or rake in games of cash games
The fees are also applicable in cash games. In tournaments, usually 10% of the entry fee will be charged in fee's. This is especially true for smaller tournaments. When you have tournaments with higher buy-ins, it is possible that the fees will be lower (lower percentage). In games of cash game, the system is different. Many poker rooms will not charge a commission (or fee) if you don't see flop (#flop #rake). If there is a flop, between 3% and 5% of the size of the pot will be taken as commission up to a maximum agreed upon beforehand (it depends on the rooms, but it is rare that a room will take more than 4 euros from a pot, regardless of the size of the pot).