Compression socks put pressure on certain points of the foot and leg to prevent swelling and increase circulation. This helps the muscles recover and perform at top levels. Exceptionally good for people on their feet all day, as they keep the blood and fluid flowing as they should.
Compression also gives great support to the wearer. For example, compression around the arch of the foot, which is commonly seen in athletic socks, gives support to the arch and helps keep you comfortable and safe from things like stress fractures.