Overlock, or overlocker, is a more British term for a Serger. The normal stitch is an overlock stitch. The stitch used for hems is a coverstitch-if you are talking about the one with 2 straight rows on top and a loopy stitch on the bottom. You can never go wrong with a Babylock serger. I am on my third serger and it's a Juki. It does pretty much everything but talk and I'm still learning it. But for finished seams and rolled edges, a serger is a must! The rolled edge is great for ruffles.