The little gold-plated circuits which recognize you as a subscriber on a particular carrier and plug into phones, tablets, and pretty much anything else with a cellular radio.
Apple hates SIMs, and has hated them for as long as the iPhone has existed: it is known to have explored the use of fixed, non-removable SIMs in the past.
Finally, with the iPad Air 2 and mini 3, Apple has decided to start making its move by using a reprogrammable SIM that can be taken from carrier to carrier, switching networks and pricing plans through user-friendly software alone. It's called "Apple SIM." Not all carriers are on board yet. Apple SIM is still removable, and carrier-bought iPads will use regular, locked SIMs BUT it is inevitable, within a year or two, you'll probably never see a SIM card in an Apple product again. Continue reading