Operating systems, with the exception of those for early home computers, are able to run multiple programs, a.k.a. processes, simultaneously. Each process runs independently and concurrently, typically on its own CPU (in multi-CPU systems), and has its own memory space, meaning that one process can’t access the memory of another (by default). In turn, processes are able to run multiple threads concurrently where each thread is typically running a different function (or the same function, but on different data) independently at any given time for improved throughput and thus performance.