A type of USB connector. USB stands for "Universal Serial Bus". Devices connected to the computer using a USB cable can flawlessly transfer files and information between the phone and the computer (if Mass Storage mode is supported files can be transferred without the need of special drivers or software).
Some devices can be charged when the USB cable is connected to the computer. There are different USB interfaces: Mini-USB (with two subtypes - Mini-A and Mini-B) is one of them,but it's in the process of being replaced by the newer and slimmer Micro-USB interface.
The miniUSB connector is still widely used, but the newer microUSB port has been the most widely adopted connectivity and charging jack on mobile phones of various makes.