A special slot for inserting a memory card. Memory cards allow you to expand the phone’s built-in memory (or in the past these slots have been used to add some missing features such as Wi-Fi connectivity).
Memory cards have different capacities and are used to store and transfer files between compatible devices. There are several types of memory cards. The most popular and frequently used by mobile phone manufacturers is microSD; however, up until recently Sony Ericsson exclusively used the Memory Stick Micro (M2) card type developed by Sony.
Memory card slots can have various supported memory card capacities. Depending on the device, card slots can support capacities of up to 2, 4, 8, 16 or even the yet unavailable 32GB.