A surgical suture is used to close the edges of a wound or incision and to repair damaged tissue. There are many kinds of sutures, with different properties suitable for various uses. Sutures can be divided into two main groups: absorbable and non-absorbable. An absorbable suture decomposes in the body. It degrades as a wound or incision heals. A non-absorbable suture resists the body's attempt to dissolve it. Non-absorbable sutures may be removed by a surgeon after a surface incision has healed.

Sutures are made from both man-made and natural materials. Natural suture materials include silk, linen, and catgut, which is actually the dried and treated intestine of a cow or sheep. Synthetic sutures are made from a variety of textiles such as nylon or polyester, formulated specifically for surgical use. Absorbable synthetic sutures are made from polyglycolic acid or other glycolide polymers. Most of the synthetic suture materials have proprietary names. The water-resistant material has been used for surgical sutures, and other sutures are made from thin metal wire.

Sutures are also classified according to their form. Some are monofilaments, that is, consisting of only one thread-like structure. Others consist of several filaments braided or twisted together. Surgeons choose which type of suture to use depending on the operation. A monofilament has what is called low tissue drag, meaning it passes smoothly through tissue. Braided or twisted sutures may have higher tissue drag, but are easier to knot and have greater knot strength. Braided sutures are usually coated to improve tissue drag. Other sutures may have a braided or twisted core within a smooth sleeve of extruded material. These are known as pseudo-monofilaments. A suture can also be classified according to its diameter. In the United States, suture diameter is represented on a scale descending from 10 to 1, and then descending again from 1-0 to 12-0. A number 9 suture is 0.0012 in (0.03 mm) in diameter, while the smallest, number 12-0, is smaller in diameter than a human hair.

Suture manufacturing comes under the regulatory control of the Food and Drug Administration (FDA) because sutures are classified as medical devices. Manufacturing guidelines and testing for the industry is provided by a non-profit, non-governmental agency called United States Pharmacopeia, located in Rockville, Maryland.