Right after I learned the glory of knitting in the round, I decided that I would do almost anything to avoid a seam. (I have since realized that some fibers hold their structure way better with seams, maybe more on that at some point.) It was then that I decided to get serious about Kitchener stitch.
Kitchener stitch is a way to join two pieces of knitting seamlessly. It is done by grafting two sets of live stitches together. If you've knit top-down socks, you've most likely encountered the Kitchener stitch at the toe, but you can use Kitchener on just about anything. The first few times you use this technique it can be frustrating, so I suggest doing the Kitchener when you can concentrate on your knitting. After a little practice, you'll be able to graft like a pro!
You'll need two sets of live stitches on two needles, a tapestry needle and a length of yarn in order to Kitchener.
Step one: Make sure the stitches are divided evenly on two needles. You MUST have the same number of stitches on each needle for Kitchener to work. If you have an odd number of stitches that doesn't divide evenly, you can knit two together to make it work out. (There may be a more professional way of doing this - feel free to share your Kitchener secrets in the comments section.) The needles should be parallel to each other with the wrong sides together.
Step two and three are set-up steps, you will only do them once.
Step two: Insert the tapestry needle into the first stitch on the front needle as if to purl and pull the yarn through. Do not drop this stitch off the needle.
Step three: Insert the tapestry needle into the first stitch on the back needle as if to knit and pull the yarn through. Do not drop this stitch off the needle.
Steps four - seven are the steps that you'll repeat for the rest of the process.
Step four: Insert the tapestry needle through the first stitch on the front needle as if to knit and slip the stitch off the needle.
Step five: Insert the tapestry needle through the next stitch on the front needle as if to purl. Pull the yarn through, but do not slip the stitch off the needle.
Step six: Insert the tapestry needle through the first stitch on the back needle as if to purl and slip the stitch off the needle.
You will repeat steps four through seven 'til the end. Once you get the hang of it, it's quite easy. Just like with picking up stitches from the side, I have a chant that goes along with this - knit - drop, purl - keep, purl - drop, knit - keep. If you're Kitchener stitching across a large number of stitches, you'll want to pull the yarn taut at various points in the middle - it's a lot easier to do than if you wait until the very end.
When you have only two stitches left, you'll skip step five. Obviously, if you have one stitch on the front and one stitch on the back, you won't be able to work two stitches on the front needle.
Kitchener stitch is pretty standard, but if you notice an error in my Kitchener instructions, please let me know at tonyawagner AT theshizknit DOT com, or leave a comment. If you have questions and would like something to be cleared up, I'm happy to help - just send me an email or comment.