Registers are special high-speed storage areas within the processor, used to hold instructions and data that are currently being executed or otherwise used. Each register has a specific size, typically expressed in bits, and serves a special purpose. The number of registers and their size vary depending on the type of processor. Some of the more common registers include the program counter (which keeps track of the current instruction to be executed), the instruction register (which holds the instruction that the processor is currently executing), and the general-purpose registers (which can contain data and instructions). The registers are the processor’s memory, and most instructions involve at least one register. They can store both data and instructions and are used to quickly manipulate information while a program is running.