1. A nitrogenous base: This is a molecule with a nitrogen-containing ring structure. There are five main types: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U).

2. A sugar: This is a five-carbon sugar molecule, either ribose (in RNA) or deoxyribose (in DNA).

3. A phosphate group: This is a molecule composed of phosphorus and oxygen atoms.

These three components bind together to form a nucleotide.