Sewing or stitching or Tailoring is the fastening of cloth, leather, furs, bark, or other flexible materials, using needle and thread. Its use is nearly universal among human populations and dates back to Paleolithic times (30,000 BCE). Sewing predates the weaving of cloth.

Sewing is used primarily to produce clothing and household furnishings such as curtains, bedclothes, upholstery, and table linens. It is also used for sails, bellows, skin boats, banners, and other items shaped out of flexible materials such as canvas and leather.

Most sewing in the industrial world is done by machines. Pieces of a garment are often first tacked together. The machine has a complex set of gears and arms that pierces thread through the layers of the cloth and semi-securely interlocks the thread.

Some people sew clothes for themselves and their families. More often home sewers sew to repair clothes, such as mending a torn seam or replacing a loose button. A person who sews for a living is known as a seamstress (from seams-mistress) or seamster (from seams-master), dressmaker, tailor, garment worker, machinist, or sweatshop worker.

"Plain" sewing is done for functional reasons: making or mending clothing or household linens. "Fancy" sewing is primarily decorative, including techniques such as shirring, smocking, embroidery, or quilting.

Sewing is the foundation for many needle arts and crafts, such as applique, canvas work, and patchwork.

While sewing is often seen as a low-skill job, the task of designing good-looking three-dimensional shapes from non-stretching two-dimensional fabric generally requires extensive hands-on knowledge of the design and principles of mathematical manifolds. Flat sheets of fabric with holes and slits cut into the fabric can curve and fold in 3D space in extensively complex ways that require a high level of skill and experience to manipulate into a smooth, ripple-free design. Aligning and orienting patterns printed or woven into the fabric further complicates the design process. Once a clothing designer with these skills has created the initial product, the fabric can then be cut using templates and sewn by manual laborers or machines.