Field Programmable Gate Array, is a pre designed circuit that can be configured (in the field) and then be given a certain functionality. It is often used for prototyping due to its large flexibility and unlimited possibility to change to a new configuration. It is also used in designs where lower volumes are expected since the FPGAs do not require large volumes, compared to ASICs, to be cost effective. There are FPGAs that can only be configured once, which can be preferred in for example end user security solutions.