This tutorial covers an I-Cord Bind Off (or Cast Off). It is also known as Applied I-Cord.
You start with the stitches you want to cast off. Begin by casting on three stitches with a cable cast on. If you were casting off in the round, you could begin this by provisionally casting on three stitches and working it that way.
Knit the first two stitches. Knit the next two stitches together through the back look.
Slip the stitches back onto the left hand needle, slipping the stitches purlwise.
Knit the first two stitches again, and knit the next two stitches together through the back loop. Slip the stitches back to the left hand needle, slipping the stitches purlwise.
Keep repeating these steps. You will get a beautiful edge to your knitting.
Repeat until you reach the last three stitches. Slip them from the right hand needle to the left hand needle. Knit the three stitches together through the back loop and cut you yarn, pulling through.
If you were knitting in the round, to finish you would graft the last three stitches together with the first three stitches, creating a seamless join to your I-cord.
The edge lays flat, with a firm tailored look.