The elementary charge, denoted by e, is the smallest unit of electric charge that can exist freely in nature. Its value is approximately:
e≈1.602×10-19coulombs (C)
The elementary charge is the positive charge carried by a single proton, as well as the negative charge carried by a single electron. Protons have a charge of +e, while electrons have a charge of −e.
The concept of the elementary charge is fundamental to understanding the behavior of electric charge at the atomic and subatomic levels.