Currently there are two distinct types of pool rewards methods in use by most pools. PPS is short for Pay Per Share and means that each share will be rewarded a fixed amount of coins depending on the current network difficulty. Miners will receive their reward independent if a pool actually finds a block or not. Miners essentially sell their hashrate to the pool for a fixed price. How and if the pool sets the price varies from pool to pool. Some base it on the block reward & the actual network difficulty, some also include an estimation of the transaction fee reward in their price. As the actual risk of finding a block lies with the pool operator this reward method is usually subject to higher pool fees. The benefit of this method is that miners will receive their reward independent if the pool actually finds a block. PPLNS is short for Pay Per Last N Shares and means that after a block is found, the block reward is distributed to all miners of the pool according to the amount of hashrate submitted during the last N hours. N can range from 1 to several hours. Usually the distributed reward includes the full block reward and all transactions fees. As the risk of finding an block lies with the miners and not the pool operator this reward method is usually subject to lower fees compared to PPS. The drawback of this method is that if a pool does not find a block for a prolonged period of time the miners will not receive any reward for their submitted hashrate.