1 Echocardiography (echo) is a painless test that uses sound waves to create pictures of your heart.  This test gives your doctor information about the size and shape of your heart and how well your heart's chambers and valves are working.
USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power.
How USB Ports Work. The rectangular socket is a typical USB socket. Connecting a USB device to a computer is simple -- you find the USB connector on the back of your machine and plug the USB connector into it. If it's a new device, the operating system auto-detects it and asks for the driver disk.