An ampere, often shortened to amp, is a unit of electric current in the International System of Units (SI). It measures the flow of electric charge through a conductor, such as a wire. One ampere is defined as one coulomb of charge passing through a point in a circuit per second. Amperes are crucial for understanding how electrical devices operate. For example, a light bulb rated at 2 amps uses more current than one rated at 1 amp. This measurement helps determine the appropriate wiring and circuit protection needed for safe electrical installations.