SIM = Subscriber Identification Module

What is SIM?

SIM is the short form of Subscriber Identification Module. It is a small sized smart card that includes a chip within it. When inserted in the SIM slot of a mobile phone, it allows the device to communicate with the network using a unique identification number by which the owner of the sim card is identified. It can also include very small amount of storage capacity to store personal data, contact numbers and SMS. When it is removed from the device, connection to the network automatically get disconnected.