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Definition: headphone jack

The analog socket used to plug in a headset, earphones or headphones. The 2.5 and 3.5 mm jacks have been used on cellphones and smartphones, while stereo and home theater equipment generally have a 6.3 mm socket. In time, the common headphone jack on smartphones is expected to become history, replaced by wireless (Bluetooth). In 2016, Apple eliminated the headphone jack on the iPhone 7, requiring wired headphones to plug into the Lightning socket. See mini-phone connector, phone connector, headphones, earphones and Lightning connector.

Headphone Jacks
The 2.5 and 3.5 mm jacks are used with mobile devices, while the 6.3 mm connectors (bottom) are typically found on non-portable equipment.