Until the 16th century the cuffs of the shirt were an undergarment, they were frilled or ruffed and allowed to be shown at the wrist. Some commentators suggest that this was a rather daring thing to do, much like exposing a hint of underpants today. Originally ties or laces with ribbons or tape ties, were used to fasten the cuffs, a practice that continued into the 19th Century. With the invention of the button, came the idea of the cuff link.
Joining two shank buttons together with a thread or a wire, would enable him to secure the open cuffs of his shirt more easily by having a buttonhole on each side of the cuff and threading the buttons through the buttonholes. In turn he wouldn’t need to pay a servant to re-sew his buttons continually. Alas the invention of the first cuff link! Information taken from "hersey.co.uk"
Today cufflinks come in all types of themes, material and sizes, especially if you are shopping from Spivey's collections.