A distributed system is a computer system composed of many smaller systems. Distributed systems generally consist of 10s, 100s, or even 1000s of networked computers working in parallel to accomplish a singular task. This approach to computing allows many less expensive computers to work together as a more powerful system. These systems can be either tightly coupled or loosely coupled. A tightly coupled distributed system would generally consist of 10s of computers centrally located with a high speed network connecting them. These systems can be very powerful and relatively inexpensive. Tightly coupled systems can move lots of data between the computers and attack huge problems that require lots of communication. A loosely coupled distributed system generally consists of 100s or 1000s of computers connected over the internet. These systems cannot communicate as quickly, so they are often used for problems where there is a lot of processing to be done and not much communication.