CISC and RISC

Instruction set - The complete set of all the instructions in machine code that can be recognised and executed by a central processing unit. 

Complex Instruction Set Computing (CISC) -  A type of microprocessor design. The CISC architecture contains a large set of computer instructions that range from very simple to very complex and specialised. 

Reduced Instruction Set Computing (RISC) -  A type of microprocessor design. The RISC architecture contains a small set of computer instructions designed to perform a limited set of operations extremely quickly.