It can be connected to your computer or device with a micro USB. Data can be sent and received between the BBC micro:bit and the computer so programs can be downloaded from Windows, Mac, Linux (including Raspberry Pi) onto the micro:bit via this USB data connection.
If possible, avoid using USB ports on computers designed for charging devices (they are often marked with a lightning bolt or 'SS'). They supply a higher current than the micro:bit is designed to handle, and you may cause damage to your micro:bit. You may introduce a USB hub between the high current port and the micro:bit to overcome this issue, providing that the hub is also not marked for high speed 'SS' use.
For more information see our article on fault finding with the micro:bit