To me, it is the "feel" of the sock on your foot and in the shoe.

I generally use mid-weight SmartWool socks because they provide a springy cushion under my foot. Moreover, they retain most of that cushion even when wet, crusted with foot sweat and toe jam, and when saturated with trail dust and powdered horse manure. A quick rinse, a little drying time and they are ready for another 20 miles. They also last nearly forever.

There are other brands that provide a similar feel but I got a lot of SmartWool mid-weights on sale a year or so back. smile

I know that a lot of hikers prefer thin nylon socks; I don't and the above is why.
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May I walk in beauty.