The current in a circuit is the rate at which electrons are flowing through it. If you consider a water piping analogy, the rate at which water flows through pipes might be measured in gallons or liters per minute. For an electrical system, a similar way of measuring current would be in electrons per second. Unfortunately, measuring electrons per second requires use of numbers that are too difficult to manage. Instead the most common unit used is amps. One amp is equal to 6.28 x 1018 electrons per second. While it’s not important to understand why this number of electrons equals an amp, it is important to understand that an amp is a huge number of electrons passing a given point at a given time.
Voltage results in current flow. And this current flow, measured in amps, is what produces the byproducts that consumers value from electricity. These include heat, which has value in the case of incandescent lights and heaters, and the creation of a magnetic field, which is the principle behind the electric motors that power air conditioners, conveyor belts, and other such devices. Because a greater amount of heat is produced as more electrons or amps flow, it is important to manage the current flow on an electrical system. This ensures the current and related heat do not exceed levels that would cause damage or produce an overload.
There are two different symbols used for current or amps: I and A. I is the scientific symbol for amps, while A is the more intuitive and commonly used abbreviation.