The purpose of liner socks is to be worn under an athletic sock to prevent chafing that leads to blisters. They can also be worn on their own as just a thin regular sock. I use these for hiking/trail running underneath my Thorlo or Columbia hiking socks to ensure that no hot spots develop. Its very effective, like having a layer of thin moleskin over my feet. Hiking stores charge a lot more for this type of sock, but these inexpensive ones are just as good as the pricier versions. If you plan to be active outdoors and your feet tend to rub on the insides of your boots or shoes, this is a good solution and will save you the pain of blisters.