eSIM (Embedded SIM) is a technology that allows devices such as smartphones, tablets, and smartwatches to connect to a mobile network. Instead of using a removable SIM card, an eSIM stores the user's mobile subscription information electronically within the device. This allows users to activate their devices and connect to a mobile network simply by downloading a mobile plan from their network operator. eSIM technology is similar to iSIM (Integrated SIM), however, the main difference between eSIM and iSIM is that eSIM is a separate chip that is installed in the device, while iSIM is integrated into the device itself.