A blind hem is a stitch on the wrong side of the fabric and you don't see the stitches on the right side of your fabric. A blind hem is done by three straight stitches and one zigzag stitch. This type of stitches is used for hemming curtains, drapes, side hems, dresses and skirts.
There are two types of blind hemming. One is stretchy fabric and the other is regular fabric. Regular fabric method requires one zigzag and three straight stitches. Only the zigzag stitches are visible on the fabric and the three straight stitches are stitches on wrong side or backside of the fabric. Stretchable fabric method requires three small zigzag stitches followed by a big zigzag stitch repeatedly. This stretchable method allows the fabric to stretch.
Blind hem can be done by hand or through machine. Sewing machine should have a specific foot called blind hem presser foot. This is located under the needle which helps to hold the fabric while sewing. Hand blind hemming is difficult than machine sewn blind hem. A few tips on how to blind hem,