A register is a small amount of storage on the CPU and is the fastest method for a CPU to access data.
There are 8 purpose registers: * EAX: accumulator register store return values from function calls. (+, -) * EDX: data register extension of EAX register, store extra data for mor complex caluculation like * and / * ECX: count register for loop operations. ECX counts downward, not upward. * ESI: source index source index for the operation and holds the location of input data stream. * EDI: destionation index points to the location where the result of data operation is stored. * ESP: stack pointer where store arguments of a function, point to the very top of the stack. * EBP: base pointer points to the bottom of the call stack. * EBX: the only register that was not designed for anything specific, is used for extra storage.