Universal Serial Bus (USB) is an industry standard which was developed in the mid-1990s to standardize the connection of computer peripherals to computers.
Being the most popular and common connector type now it replaced a lot of earlier interfaces.
A number of cables have a type-A connector on one end, most peripherals (such as keyboards and mouse) have a type-A connector, personal computers usually have multiple Type-A ports, and many other devices and power adapters use a type-A port for data transfers along with charging.
USB Type-A connectors are supported in every USB version, either it is USB 3.0, USB 2.0, or USB 1.1.
The male USB Type A connector is called the plug and the female connector is called the receptacle but is commonly known as the port.
These are found on host controllers in computers and hubs, the A-style connector is flat with rectangular interface. This interface holds the connection in place by friction which makes it very easy to connect and disconnect.
Instead of round pins, the connector uses flat contacts which can hold continuous attachment and removal very well. The A-socket connector provides a “downstream” connection that is intended for use solely on host controllers and hubs.
It was not designed to be used as an “upstream” connector on a peripheral device. This is critical because a host controller or hub is designed to provide 5V DC power on one of the USB pins. Though not that common, A-A cables are used to connect USB devices with an A-style Female port to a PC or another USB device, and for data transfer between two computer systems.
Typically an A-A cable is not intended to connect two computers together or to connect a USB hub between two computers. Doing so may cause irreparable damage to your computers and may even present a fire hazard. Check with the manufacturer before using an A-A cable for data transfer.