For the longest time I had no idea what cufflinks were. I knew that guys wore them when they dressed up fancy but I couldn't figure out why. Eventually I learned that there are shirts that are actually made without buttons on the sleeves and cufflinks are used instead to hold the cuffs together. Of course I never actually see anybody wearing them, so I don't know how popular it is here. I think it's more popular in other countries or in high class societies.