eSIM
Embedded SIM
An alternative to physical, removable SIM cards that instead embeds SIM functionality into the phone hardware.
See: SIM
Instead of swapping physical cards to associate a phone with a different account (and phone number), the change is made in software over the network.
eSIM uses far less physical space inside a phone than a SIM card slot, and enables cellular functionality in devices too small to accommodate physical SIM cards, such as smartwatches.
eSIM can also provide more functionality and flexibility, as it can be reprogrammed to support new network features that would require a whole new SIM card with a physical SIM card.
