How to Graft (Kitchener) Stitch
Grafting (also something called Kitchener) Stitch is a technique which seamlessly joins two sections of knitting that have live stitches. Live stitches mean the stitches don't have a straight bound off or cast on edge, but they are free to be worked on (or unravelled) as needed.
This technique is commonly used in knitting to create an invisible and smooth seam, particularly for finishing the toes of socks or joining the shoulders of a garment. The result is a seamless and continuous piece of fabric without a visible seam.
It's very common for the stitches to look a little crooked once you've finished so you'll want to play with the stitches afterward to create an even tension. To begin with, just focus on getting the knitwise / purlwise movements correct.
It's tough to remember which stitches are purlwise and which are knitwise. So here's a handy tip and a cheat sheet for you. Feel free to Pin it for later or screenshot it to save on your phone:
The front needle will have the knit stitches facing you and the back needle will have purl stitches facing you. So start knitwise on the front needle (because the knit stitches face you) and purlwise on the back needle (because the purl stitches face you).