Measurement of current, the movement of one coulomb of charge in one second. Depending on the application, a few milliamps can be a lot of current whereas in power applications, thousands of amps is the norm.
Ohm’s law - The voltage v across a resistor is directly proportional to the current i flowing through the resistor.
Fundamentals of Electric Circuits, 5th Edition by Charles K. Alexander and Matthew N. O. Sadiku
The basic unit of current. 1A=1C/1s or 1A=1V/1Ω.
Grob’s Basic Electronics, 11th Edition by Mitchel E. Schultz
The ampere (/ˈæmpɪər, æmˈpɪər/ or /ˈæmpɛər/ (UK), symbol: A), often shortened to "amp", is the base unit of electric current in the International System of Units (SI). It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics.
The International System of Units defines the ampere in terms of other base units by measuring the electromagnetic force between electrical conductors carrying electric current. The earlier CGS measurement system had two different definitions of current, one essentially the same as the SI's and the other using electric charge as the base unit, with the unit of charge defined by measuring the force between two charged metal plates. The ampere was then defined as one coulomb of charge per second. In SI, the unit of charge, the coulomb, is defined as the charge carried by one ampere during one second.