The micro:bit has a USB type-B micro connector.
You can use the USB interface to load code onto the micro:bit, and to power it.
The USB lead that you require will depend on what computer you are plugging the micro:bit in to, but for the majority of cases, you want a USB type-A connector at the computer end, and a USB micro-B plug at the micro:bit end. Newer computers have USB type-C (a small round connector that you can plug in any way around)
You will need to make sure that this cable is designed to be a data transfer cable (i.e. it has all of the wires inside it populated) rather than just being a charging cable. Some charging cables that come with mobile phones and other portable devices only have the power wires fitted - which means that your micro:bit will power up when plugged into the USB of your computer, but you will not be able to drag and drop code on to it.
When the micro:bit is powered from USB, the yellow system LED on the back will light.
If a successful data connection is made over your USB cable, your computer will add a MICROBIT drive into the file manager view. If it is unsuccessful and you are sure yo are using the correct type of cable, follow our advice on fault finding with a microbit