An element is a substance that cannot be broken down into any simpler substance by chemical means. It is made up of only one type of atom, and each atom in a given element has the same number of protons in its nucleus, which is called the atomic number. Different elements have different numbers of protons, which makes each element unique. For example, hydrogen has one proton, carbon has six, and gold has 79. Elements are the basic building blocks of all matter and are listed in the periodic table. There are about 118 known elements, with around 92 occurring naturally on Earth.

In summary, an element is a pure chemical substance consisting of only one kind of atom that cannot be chemically broken down further and is characterized by its atomic number.