A serger is a sewing machine that finishes a seam at the same time as sewing it. You can sew a seam, overcast the edge and trim the excess fabric with one pass of your serger. These machines are helpful in achieving a finished look on clothing, but there are alternatives, like a zig zag stitch that can be done on your regular sewing machine.
Do you need a serger? Check out our post: Do I really need a ______________ ?