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.
After appearing in 1997, USB became the standard for connecting keyboards, mice, printers and hard drives, eventually replacing the PC's serial and parallel ports and the Apple Desktop Bus on Macs (see serial port, parallel port and ADB).