IMHO, the neatest thing about this heel is that it is self-contained and, therefore, can be knit after the rest of the sock is done and is easily replaced. I think of it as the Depression-era homemade sock... when handknit socks were common and, perhaps, made more out of economic necessity than personal style. It is also called a grandmother's heel and a waste-yarn heel. To make this heel, knit to where the heel will begin, knit X amount of stitches (X being the number of intended heel stitches) on waste yarn, put those X stitches back on the left needle, and reknit them with the sock yarn. After completing the sock, take out the waste yarn and put the resulting loops on facing needles (one needle will have one more loop than the other!) and "make a heel." Generally the heel is similar to a toe and, in many socks, the heel and toe are shaped identically, both being shaped by double-decreasing. Elizabeth Zimmermann offers her "afterthought heel" which differs from the grandmother's heel in that you do not knit a "marker" with waste yarn, but knit the sock with no heel or heel placement. After the sock is completed, you determine where to place the heel and carefully snip a section of yarn to release the opposing loops. Pick up the newly-freed stitch loops and make a heel. The advantage to this is the ability to determine exact heel width and placement. Variations
Because of the double-decreasing, it looks a little like the short-rowed heel, or commercially-knitted socks, with a textured row (in this case the matched decreases) forming a straight line, at a 45-degree angle, from the bottom, back of the heel up to the ankle. There are many variations of matched double-decreases to play with and, yielding different textures and stylistic effects. To replace or reknit peasant heel
Just carefully unravel the heel and make another one.
Again, Folk Socks has a few patterns that use this heel, including the Ukrainian Socks...