Is used to temporarily hold small units of program instructions and data immediately before, during, and after execution by the central processing unit (cpu).

A register

Explanation:

Registers are small memory used to store data or values and supply them to the processor as and when needed. These register hold the data temporarily and hold small units of program instructions. So whenever the CPU wants to work on data they have to be made available through the registers. Even after a arithmetic operation the registers serve as buckets for holding the value.

There are different types of registers such as register A, B, C etc and these registers lie in close proximity to the CPU so that we could provide the data immediately and much faster when asked by the CPU.

Therefore we can say that registers are used to temporarily hold small units of program instructions and data immediately before, during, and after execution by the central processing unit (CPU).