Hold the two pieces you want to bind together with right sides facing each other. You want them to be aligned on top of each other in your left hand (assuming you normally hold your knitting in your left hand). Put the point of another needle into the first stitch of each needle knit-wise and knit them together. Continue on to the next two stitches, binding off as you go. After a few stitches, turn it over and see how it looks. You may need to adjust your tension to get it to look right.
The explanation from Maia is great. I use this all the time. I'll never seam the sole of a bootie again! Here are a few places I found on the web that have pictures to show you.
This one is for a sweater shoulder seam (Hmm. Looks like a flat, not shaped, shoulder, but I'm hoping to use it for a stepped shoulder. I'll have to experiment.)
There's a video thatI haven't been able to watch on my computer (yet) but the pictures show you what the finished product looks like.
This has some good pictures of the process and the finished look.
and so forth. All I did was use google and type in: three needle bind off and I came up with lots of hits. I love this technique!! (You couldn't tell, right? )
>I'm hoping to use it for a stepped shoulder< Use short rows for your shoulders leaving live stitches along the edges that can be used for the bind off.