The jack connector (also known as a jack or simply jack) is an electrical connector used to carry signals (mostly audio in analog form) in very low voltage.

The male jack connector has a cylindrical shape and can have two to five contacts. To indicate the quantity and position of the contacts the acronyms are used: TS, TRS, TRRS and TRRRS, respectively 2, 3, 4 and 5 contacts. These letters derive from the initials of the following English words: Tip (tip) corresponds to the tip of the connector; Ring (ring) for the central parts; Sleeve (sleeve) for the connector base, often used as a mass. For example, a common stereo headphone jack is identified as "TRS jack", as it has three contacts: the tip (T), a central ring (R) and the base sleeve S).

The jack connector is also produced in different diameters, in its original configuration the external diameter of the connector that acts as a conductor is 1/4 of an inch (6.35 mm). Later, smaller, "mini" 3.5mm diameter and 2.5mm "sub" mini variants were produced, as well as a larger 7.13mm variant used in civil and military aviation.