When you plug in your headphones to your phone, a guitar into an amp or a mic into a mixer, you’re using a technology that goes back to 1878. It’s that thing on the tip of the cord that leads to your device: the connector jack.
And no, that was wasn’t a typo. I really did mean to say “1878.”
The quarter-inch version–6.35 mm in metric-speak–was invented as a quick-connect method by some clever boffin in the late 19th century for telephone switchboards when operators had to patch calls manually. Later–much later–we got the 3.5 mm version, which is what you use to plug in your ear buds.
Officially called a TRS connector (f0r “tip,” “ring” and “sleeve,” the three components that make it work), the thing has served us well over the centuries (!!!) but is now facing possible extinction as manufacturers are looking for connectors capable of transmitting more bandwidth, especially for the growing adoption of Hi-Res Audio. Apple, for example, is rumoured to be phasing out the 3.5 mm jack in favour of connecting a new generation of headphones and other peripherals through its Lightning port.
Read more about the old, reliable TRS jack at the BBC.