A pool is a group of miners who agree to gather all the power of their equipment to find the bitcoins more easily. When any of them finds a bitcoin, the profits are shared. Basically they do, joining efforts, what other companies engaged in bitcoin mining do: use hundreds of computers to mine. These groups that have been formed through the big world, have given the opportunity to inexperienced in bitcoin to develop within the world of mining and create their own profits through a CPU. Many others, they start to know how to operate until they understand and improve their equipment to improve mining. So yes, mining, above all, you have lowered unemployment rates to a high level.