A "Micro SIM" is a smaller version of the traditional SIM (Subscriber Identity Module) card. Introduced in 2003, it measures 15 mm x 12 mm, making it significantly smaller than the standard SIM card. Despite its reduced size, it retains the same functionality and stores personal data such as the mobile number, service provider details, and contacts. It was commonly utilised in early smartphone models due to its compact size, which allows for sleeker phone designs. The only difference between a Micro SIM and its predecessors is the amount of plastic surrounding the chip. It was slowly phased out in favour of the Nano SIM in smartphones, but remained popular in 4G-5G modems for many years.