Afterthought heels are common in socks knit with self-striping yarn, because the striping pattern isn't interrupted across the instep (top of the foot) of the sock. Afterthought heels also work nicely when you want the heel of your knit sock to be a color that contrasts with the rest of your sock.
Afterthought heels can be used in socks knit from the toe up or from the leg down. I prefer to knit afterthought heels on dpns, but you could also use the magic loop method.
The basic idea of an afterthought heel is that you knit the entire sock, and then go back and insert the heel at the end. It sounds scary at first, but let me show you how simple it actually is.
If you are new to sock knitting, you will likely knit your sock from the leg down. Knit the entire leg of the sock.
Placing an afterthought heel
There's a reason that piece of white yarn is considered waste yarn. It needs to be removed from the sock, but before you do, you need to pick up the stitches on either side.
In my next post I'll show you how to knit the perfect, no gap, afterthough heel.