There are several different iron oxides, but the most common one is iron(III) oxide, also known as ferric oxide, with the chemical formula Fe₂O₃. This is the reddish-brown compound that makes up rust.

Here are some other common iron oxides:

* Iron(II) oxide, also known as ferrous oxide, with the chemical formula FeO.

* Iron(II,III) oxide, also known as magnetite, with the chemical formula Fe₃O₄.

Let me know if you'd like to learn more about any of these iron oxides!