Definition of staking
"Staking" means buying stock from a poker player. The word "staking" should not be confused with the word "stacking" (taking all of a player's chips because you have won a hand). Some people will want to buy action from winning poker players. You can buy some or all of your action from a cash game or a tournament. There are many forms of staking because it's all about the deal you have with the player you stake.
An example of a staking
A player is a big winner at NL200€. He has the bankroll to play NL200, but with his current expenses, he cannot afford to go up to NL400€. A wealthier player might say "I'll give you staking". When he goes staking, he provides him with the money he needs to play at the limit discussed. Typically, 50% of the player's profits will go to the staking player and the other half will be kept by the player. The staking player takes all the risk. If the player loses money in the NL400, the staking-player will have to pay. The same principle also applies to tournaments.