An eSIM is a SIM-card that is embedded in the mobile device. The SIM stores all information that is necessary to identify and authenticate the mobile subscriber.
An eSIM will come in the form of an integrated SIM chip that cannot and need not be removed from a device. The eSIM is sometimes called an eUICC (embedded Universal Circuit Card). The information on the eSIM will be compliant and rewritable by all operators. The identification information can be updated over the air, to enable a change of operator. A new SIM will no longer be required.
The driver for eSIM comes from the difficulty to change a SIM card in M2M devices, such as smart meters. However, it will also be used in mobile user equipment. One of the first manufacturers that started to use an eSIM was Apple. The Apple SIM was introduces in iPads in the United States.
The eSIM is specified by GSMA.