In computer science, a pool is a collection of resources that are kept in memory, ready to use, rather than the memory acquired on use or the memory released afterwards. In this context, resources can refer to system resources such as file handles, which are external to a process, or internal resources such as objects. A pool client requests a resource from the pool and performs desired operations on the returned resource. When the client finishes its use of the resource, it is returned to the pool rather than released and lost.