The most common form of hydrogen has one proton and one electron, and is known as protium.

Here's why:

* Protium accounts for about 99.98% of all hydrogen atoms found in nature.

* Deuterium, another isotope of hydrogen, has one proton, one neutron, and one electron.

* Tritium, the rarest isotope, has one proton, two neutrons, and one electron.

So, when people talk about hydrogen, they are usually referring to protium.