Here's why this is important:

* Uniqueness: Every element has a unique atomic number. This means that each element has a specific, unchanging number of protons in its atoms.

* Identity: The atomic number defines the element. If an atom has 6 protons, it's a carbon atom, no matter how many neutrons or electrons it has.

* Chemical Behavior: The number of protons determines the number of electrons an atom will have in a neutral state. This arrangement of electrons dictates how the atom will interact with other atoms, leading to the element's chemical properties.

For example:

* Hydrogen has an atomic number of 1, meaning it has 1 proton.

* Oxygen has an atomic number of 8, meaning it has 8 protons.

* Gold has an atomic number of 79, meaning it has 79 protons.