I had to try and explain what a serial in parallel out shift register does, and came up with this, which might be of some use to newcomers.
A postman ( mailman ) has to deliver 10 parcels to 10 houses in a row, he can only carry one at a time, so to save a lot of walking, he comes up with the idea of parking at the end house and tooting his horn ( taking the latch pin low ) to call the people out of their houses to their front gardens.
He then gives the parcel for the furthest house to the lady at the first house, and asks her ( taking the shift register clock high and low again ) to pass it to the next lady.
He then gives her the second parcel and shouts to everyone to pass them on ( pulsing the shift clock again )
When all the parcels have been passed out , he tells them to take them indoors and open them ( by taking the latch pin high again )
In practice this save a lot of wiring ( walking ) and a great many devices can be connected to shift data to the right device, such as LED displays which would need thousands of individual wires to light the correct patterns.