What is a 3.5mm Headset Jack and a 3.5mm Headset Connector?

A 3.5mm headset jack is a 3.5mm diameter port for headset. It is used on some computers and some cell phones.

A 3.5mm connector is a small round pin connector in 3.5mm diameter, with 3 black rings. It connects headset to older smartphone models, like iPhone 6 and before.