T flip-flop means ___
T flip-flop means the "toggle" flip-flop changes its output on each clock edge, giving an output which is half the frequency of the signal to the T input. It can be made from a J-K flip-flop by tying both of its inputs high. It is useful for constructing binary counters, frequency dividers, and general binary addition devices.
Registers are used to store multiple bits of data. So flip flops are used to design registers. According to digital electronics, a register is a device which is used to store the information.