A saxophone is a single reed constructed from brass with a curved bottom woodwind instrument first developed in the mid-1800s by Adolphe Sax. It is composed of a mouthpiece, conical metal tube, and finger keys. Sound is produced when air is blown through the instrument causing the reed to vibrate. This sound is amplified as it travels through the instrument's main body. Saxophones consist of numerous parts and pieces which are made separately and then assembled.

Originally available in 14 different sizes and keys, today that number has been reduced to six. This includes—in order of pitch from highest to lowest—the sopranino, soprano, alto, tenor, baritone, and bass saxophones. Generally, the smallest instrument is the sopranino and the largest is the bass.

The saxophone mouthpiece is the part of the instrument that the musician blows in to produce the sound. The construction of the mouthpiece has an important effect on the final sound of the instrument. It makes the difference between the sax player in a symphony orchestra and one in a rock band. There are two main parts of the mouthpiece that affect tone: the tone chamber and the lay (or the facing) which is the opening between the mouthpiece's reed and its tip. Mouthpieces are typically marked with a letter or number to denote the width of the lay.

The reed is attached to the saxophone and vibrates to create the sound. Saxophone reeds are made from bamboo (Arundo donax) which is grown in southern France. The reed can be made soft or hard depending on the desire of the musician. The ligature is the part that holds the reed on the mouthpiece. It attaches to the mouthpiece with screws. They can be made from innumerable materials such as leather, metal, or plastic.

The crook is the part that joins the mouthpiece and the main instrument body. At the top of it is a cork which is important for tuning the instrument. The tone changes depending on where the mouthpiece is positioned on the cork. The other end of the crook is a metal joint that fits into the main body of the saxophone. It connects with a screw to keep the crook in place.

Saxophone keys are of two types, closed standing and open standing. Closed standing keys are those that are held closed by a spring when the instrument is not being played. When the key is pressed, the hole it covers is opened. Open standing keys are held open by a spring and close when the key is pressed. Each key has a pad on its end which provides an airtight seal on the hole.

The saxophone tube is a long, metal tube which steadily gets wider at one end. It has holes drilled in the side at specific spots to create notes. When all the holes are closed, the instrument works much like a bugle amplifying the sound of the vibrating reed. When a hole is opened, the sound is modified producing a different note. The conical shape of the saxophone makes the overtones octaves. This makes fingering easier because the higher pitched notes are produced with the same fingering as lower pitched ones.

Saxophones are primarily made from brass. Brass is a composite alloy made up of metals including copper, tin, nickel, and zinc. The most common type used for instruments is yellow brass which contains 70% copper and 30% zinc. Other types include gold brass and silver brass which have different ratios. The zinc in brass makes the alloy workable at lower temperatures. Some custom manufacturers use special blends of brass for different saxophone parts. A small amount of arsenic or phosphorous also may be added to make the brass more useful in tubing applications.

Other materials are used to make the saxophone. Most of the screws are composed of stainless steel. Cork is used to line the joints and water keys. In some cases, a wax is applied to these joints. Mouthpieces can be made from various materials, however, the material has little effect on the sound. The most common material is black, hard rubber or ebonite. Metal or glass mouthpieces are also available. Plastic resonators are made and the instrument is often coated with a lacquer. Nickel plating on the keys helps strengthen them and keeps them attractive.