What is a Shift Register?

Hi
Shift registers are nothing but a flip flops connected serially,thus they can store bits of data.
Shift registers are mainly used to shift data and convert information from serial to parallel and vice versa,
and it can also be used as counters for counting and thus can be used as delay circuit
for more information check this link hope this will help u:
<a href="https://en.wikipedia.org/wiki/Shift_register" target="_blank" rel="nofollow noopener noreferrer">Shift Register</a>