Sewing machines are an essential tool for those who want to make their own clothes, repair or alter existing ones, or try their hand at different projects. They can be traditional electric sewing machines or more modern computer-controlled models that offer a variety of stitches and functions. Sewing machines can be used to sew different fabrics such as cotton, silk, denim and leather, and to make a variety of sewing and decorative stitches. Their features can include different stitch and seam options, automatic thread attachment and thread tension adjustment.