What is the definition and function of the USB data cable?

How many cables are there in the USB data cable? What are their respective functions? There are four cables in the USB data cable, two power supplies and two signals, which are red (power), white (signal), green (signal) and black (power). Let's learn about the specific functions.

1. red line: positive pole of power supply (the mark on the wiring is +5v or VCC),
White line: negative voltage data line (marked as data- or USB port -)
Green line: positive voltage data line (marked as data+ or USB port +)
Black wire: grounding (marked as: ground or GND).
Of course, the color of the wire can only be seen when peeling off the outer rubber of the data line or charging line.

2. USB devices are convenient for users to carry a lot of information with them. Naturally USB hard disk is the main choice. It is common for everyone to have IDE interface hard disk, serial port communication mouse and keyboard, and parallel port printer scanner. However, after having USB, this kind of external device can be connected to personal computer with the same specifications. At this time, we have USB hard disk, USB computer mouse, USB copier, etc.

3. The four USB cables shall not be connected randomly. The order of the four cables is certain, but there are two directions. If the two data cables are connected incorrectly, the USB device will be unable to be recognized. However, the two data cables must not be inserted incorrectly. The current that can be supplied by each USB interface should be +5v500ma. If the connection is wrong, the USB device will be burned, and the computer motherboard will be damaged.