An overlock stitch sews over the edge of one or two pieces of cloth for edging, hemming or seaming. Usually an overlock sewing machine

Sewing machine

A sewing machine is a textile machine used to stitch fabric, cards and other material together with thread. Sewing machines were invented during the first Industrial Revolution to decrease the amount of manual sewing work performed in clothing companies...

 will cut the edges of the cloth as they are fed through (such machines are called ‘sergers’ in North America), though some are made without cutters. The inclusion of automated cutters allows overlock machines to create finished seams easily and quickly. An overlock sewing machine differs from a lockstitch

Lockstitch

A lockstitch is the most common mechanical stitch made by a sewing machine. The term "single needle stitching", often found on dress shirt labels, refers to lockstitch.-Structure:...

 sewing machine in that it uses loopers fed by multiple thread cones rather than a bobbin.