• Liners- Sock liners are thin, lightweight wicking socks designed to be worn right next to your skin. These liners wick sweat away from the surface of your foot to keep you dry and more comfortable. Liners also limit the amount of abrasion between your outer sock and your skin. They are designed to be worn under other socks.
• Lightweight hiking/backpacking socks- Designed for warm conditions and easy trails, lightweight backpacking socks stress wicking performance and comfort over warmth. These socks are thicker, warmer and more durable than liners alone. They also provide more cushioning. But they are relatively thin so that you can stay comfortable on warm weather trips. Because most lightweight backpacking socks are made from wicking materials, they can be worn with or without liner socks.
• Midweight hiking/backpacking socks- These socks are designed to provide reliable cushioning and insulation in moderate to cold conditions. They tend to be thicker and warmer than lightweight hiking socks. Many models have extra padding built into high-impact areas like the heel and the ball of the foot for maximum comfort. These socks should be worn with liners.
• Mountaineering socks- Mountaineering socks are the thickest, warmest and most cushioned socks available. They are designed for long trips, tough terrain and cold temperatures. Usually, mountaineering socks are too thick and warm for basic backpacking journeys in warm conditions.

• Wool- Wool is an extremely popular natural sock material. It is warm, cushioning, and retains heat when wet. Unfortunately, wool can take a long time to dry and it can be scratchy next to your skin (NOTE: many new wool options, including mohair, do not have this problem). It can also wear out quickly if not reinforced with other materials. Wool blends (combinations of wool and synthetic materials) are extremely popular because they address many of these problems.
• Synthetic insulating materials- A number of man-made materials designed to insulate like wool and wick moisture, without the negatives mentioned above. These materials (Hollofil(R), Thermax(R), Thermastat(R)) trap warmth like wool, but they are softer on the skin. They also dry more quickly and are more abrasion resistant. These materials are available in a variety of sock styles and thicknesses.
• Silk- Silk is a natural insulator. It's comfortable and lightweight, but not as durable as other options. It's occasionally used in sock liners for reliable wicking.
• Synthetics wicking materials- The synthetic wicking materials (like polypropylene and Coolmax) used in wicking sock liners are often woven into thicker backpacking socks as well, to enhance wicking performance.
• Cotton- 100% cotton is not recommended as a sock material for backpacking. Cotton absorbs sweat, dries slowly, provides no insulation when wet and it can lead to discomfort and blisters out on the trail. However, cotton is extremely comfortable. And when combined with wool or other wicking and insulating fibers, cotton can be a great choice for light hiking in summer.

Cushioning materials- Many backpacking socks provide extra cushioning around the heel, the ball of the foot and the toe area to increase comfort. The padding is created either by increasing the density of the weave in those areas, or in some cases by weaving long-wearing materials like acrylic into those areas. This extra padding can be a real foot-saver on hard trips over rough terrain.

Support materials- Many of today's hiking socks include a small percentage of either stretch nylon or Lycra(R) spandex. These elastic materials help socks hold their shape and keep bunching and wrinkling to a minimum.

When possible, take a quick walk in the sock styles you are considering to get a feel for how much cushioning they have. And be sure to buy the right size--your socks should fit snugly. Bunched up sock material can make any backpacking trip an uncomfortable one.