ARM Holdings plc (ARM) is a British multinational semiconductor and software design company headquartered in Cambridge, England. Its primary business is in the design of ARM processors (CPUs), although it also designs software development tools under the DS-5, RealView and Keil brands, as well as systems and platforms, system-on-a-chip (SoC) infrastructure and software. It is considered to be market dominant in the field of processors for mobile phones (smartphones or otherwise) and tablet computers. The company is one of the best-known 'Silicon Fen' companies.