Jack plugs are extremely common connectors used for musical instruments, PA mixers and DJ mixers. You'll find them in both male and female versions. They're available in 3.5 mm, also known as mini jack, and 6.4 mm, known as 1/4-inch jacks. There are also 2.5mm and 4.4mm jacks, but these are much less common. The former is usually used for a charger, or to connect a headset to a mobile phone, and the latter is often found in professional studio environments. Jack plugs are also known as TRS plugs, which stands for the three segments of the plug: the Tip Ring and Sleeve.
