How To Crochet A Seamless Join in the Round
I use the seamless join whenever I finish off circles to ensure that the edges look nice and smooth (e.g. crocheted eyes and noses). The seamless join is also very useful when finishing off crochet projects that are not circular (like a granny square).
The way the seamless join works is that it creates a false stitch on top of the first stitch of the next round. Having the false stitch on top of your first stitch lifts that edge up slightly so that there is no longer a significant height difference in your stitches.
Watch the video below to learn how to do this: