A ligature is a device which holds a reed on to the mouthpiece

Mouthpiece (woodwind)

The mouthpiece of a woodwind instrument is that part of the instrument which is placed partly in the player's mouth. Single-reed instruments, capped double-reed instruments, and fipple flutes have mouthpieces while exposed double-reed instruments and open flutes do not.-Single-reed instruments:On...

 of a single-reed instrument

Single-reed instrument

A single-reed instrument is a woodwind instrument that uses only one reed to produce sound. Examples include clarinets, saxophones, and some bagpipes. In a single-reed instrument, the reed is attached to a mouthpiece that is blown into to vibrate the reed, producing the sound...

 such as a saxophone

Saxophone

The saxophone is a conical-bore transposing musical instrument that is a member of the woodwind family. Saxophones are usually made of brass and played with a single-reed mouthpiece similar to that of the clarinet. The saxophone was invented by the Belgian instrument maker Adolphe Sax in 1846...

 or clarinet

Clarinet

The clarinet is a musical instrument of woodwind type. The name derives from adding the suffix -et to the Italian word clarino , as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed...

. The ligature must allow the reed to vibrate freely without stifling its vibrations. Iwan Müller invented a metal ligature to replace twine. String is still used by clarinetists, especially in Germany. Modern German mouthpieces have a groove cut into the outside of the mouthpiece to facilitate wrapping with a string ligature. Some modern clarinetists tie a shoestring around the mouthpiece to use as a ligature instead of a string because it is easier to tie.

A ligature must be placed properly in order to best help performance on a reed instrument. The ligature must be slid down to where it is halfway down the thick part of the reed and the screws must not be overtightened.

Ligatures are most commonly made out of metal and plated in nickel, silver, or gold. Some ligatures have rounded metal plates on the screws inside the band which wraps around the mouthpiece, giving the reed a place to lay evenly against without damaging the cane.

Ligatures are also made out of wire, wire mesh, plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

, naugahyde

Naugahyde

Naugahyde is an American brand of artificial leather . Naugahyde is a composite of a knit fabric backing and polyvinyl chloride plastic coating. It was developed by United States Rubber Company, and is now manufactured and sold by the Uniroyal Engineered Products division of Michelin...

, string, or leather

Leather

Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

. Dozens of styles and materials of ligatures are available today. Many modern Clarinetists utilise electrical tape as a ligature.