What is the charge of a proton or electron called?

The charge of a proton or an electron is indeed referred to as the elementary charge. This fundamental unit of electric charge represents the smallest charge that can exist independently in nature. The magnitude of the elementary charge is approximately 1.6 x 10^-19 coulombs.

While the answer provided specifies a numerical value, it's essential to recognize that the term "elementary charge" is what broadly describes this intrinsic property of protons and electrons. The numerical value not only reflects the actual charge but also serves to define the elementary charge in a practical sense.

Understanding this concept is crucial as it serves as the foundation for discussions around electric charge, atomic structure, and particles in physics.