Hydrogen is made up of just one proton and one electron. It's the simplest element in the periodic table.

Here's a breakdown:

* Proton: A positively charged particle located in the atom's nucleus.

* Electron: A negatively charged particle that orbits the nucleus.

While most hydrogen atoms have only one proton and one electron, there are also isotopes of hydrogen:

* Deuterium: Contains one proton and one neutron in its nucleus.

* Tritium: Contains one proton and two neutrons in its nucleus.

These isotopes are still considered hydrogen because they have the same number of protons (which determines the element).