These socks use combed cotton yarn, which is a very soft version of regular cotton. Combed cotton doesn't have any impurities or short protruding threads, is stronger than regular cotton, and is made by treating the cotton fibers before they are spun into yarn.
They are the best socks ever! I can walk around for 15+ hours in a day and they stay dry and fluffy. My last pair from a year ago still looks new after many washes.