ARM

ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured for various environments. Arm Ltd. develops the architectures and licenses them to other companies, who design their own products that implement one or more of those architectures, including system on a chip (SoC) and system on module (SOM) designs, that incorporate different components such as memory, interfaces, and radios. It also designs cores that implement these instruction set architectures and licenses these designs to many companies that incorporate those core designs into their own products.

Quotes

 * I've been personally pretty disappointed with ARM as a hardware platform, not as an instruction set, though I've had my issues there, too.
 * Linus Torvalds, Why Linux pioneer Linus Torvalds prefers x86 over ARM (October 7, 2016), Computerworld