Amperes, commonly called amps, are the units used to measure electric current. In an electrical system, the current is determined by electrons per second. But since this number is so large, we use amps instead. 1 amp = 6.28 x 1018 electrons/second or 628 with sixteen zeroes behind it (6,280,000,000,000,000,000 electrons per second moving past a point). As you can see, measuring current in electrons/second would be cumbersome, so think of an amp as a huge number of electrons per second. To give you a sense of the size of an amp, a typical home electric service in the U.S. is either 100 or 200 amps.
The scientific symbol for amperage is an "I", dating back to the early days of electricity. Scientists and engineers use the "I" symbol for amperage, while electricians and wiring books use "A" as the amperage symbol. The unit ampere is named after the French physicist Andre M. Ampere (1775-1836).