In sewing, to tack or baste is to make quick, temporary stitching intended to be removed. Tacking is used in a variety of ways:

• To temporarily hold a seam or trim in place until it can be permanently sewn, usually with a long running stitch made by hand or machine called a tacking stitch or basting stitch.

• X-shaped tacking switches are also very common on vents (slits) on the back of men's suit jacket. They are meant to hold the flaps in place during shipping and when on display in the store. They should be removed before being worn; however many buyers do not realize it. Brand labels loosely basted on the outer edges of the sleeves of suits as well as women's winter coat should also be removed after purchase. They are meant to help customers to easily identify the brands in the store without reaching into the collar.

• To temporarily attach a lace collar, ruffles, or other trim to clothing so that the attached article may be removed easily for cleaning or to be worn with a different garment. For this purpose, tacking stitches are sewn by hand in such a way that they are almost invisible from the outside of the garment.

• To transfer pattern markings to fabric, or to otherwise mark the point where two pieces of fabric are to be joined. A special loose looped stitch used for this purpose is called a tack or tailor's tack.

• A basting stitch is essentially a straight stitch, sewn with long stitches and unfinished ends. The basting stitch is used for temporarily holding sandwiched pieces of fabric in place. The stitch is removed after the piece is finished. Often used in quilting or embroidery.