The headphone jack is available all through the Apple lineup of iPhones, except for the iPhone X. Both the iPhone 7 and the iPhone 7 Plus feature the 3.5mm headphone jack and they also support audio output through the lightning port as well. The headphone jack was quite popular as an audio output during the year that the iPhone 7 and its bigger sibling, the iPhone 7 Plus, were launched. Only an year later, the company decided to do away with the headphone jack on the iPhone X.