Let's talk about sox...
(Part One-fibers)

Socks are an extremely important piece of equipment. Often overlooked, they ensure a good fit and comfortable feet.

Tip #1 - Bring your socks or buy a pair when you try on new shoes. Socks can alter your shoe size by half a size. Also, the try-on socks at most stores are not washed as much as you would hope!

The truth behind "the fabric of our lives" ie cotton.

a) Cotton WICKS! Unfortunately, it also absorbs. This keeps your skin moist and soft so any rubbing will cause a blister.
b) Cotton is fine for anyone doing relatively low miles (of course, what are relatively low miles?). Unless you are prone to blistering, cotton will be fine. Personally, I find cotton socks to be rough and heavy (especially after soaking up a couple of miles of sweat).
c) I usually recommend going to synthetics when your runs begin getting over 45 min to 1 hour.

Ah synthetics!!!

The most popular synthetic for socks is Polyester. Now those of you old enough to remember the fashions of the 70's can relax, we are not talking leisure suits! Coolmax is the best known polyester. Remember, not all polyester socks are Coolmax. The socks I have been using most are a brand called Balega. Super soft, no raised toe seam and they wick like a furry cat.

The next most popular fiber is acrylic. Wigwam Ironman and the old classic Thorlos are two popular brands. My take on acrylic vs poly is (according to my feet), poly socks keep my feet cooler but my feet feel dryer (and warmer) with acrylic.

Nylon is becoming more popular for socks also.

Wool-yes I know it isn't a synthetic, I just wanted to see if you are still awake.
Wool is seen a lot more in running socks with the popularity of Smartwool. Now everyone makes a merino wool sock. Merino wool is softer and not as itchy as regular wool. I still find them to be a little itchy and very warm. By far the best I have tried are the Smartwool, but I still only use them on cold days.

Part 2 - Trends and proper fit....