1. A nitrogenous base: This is a molecule containing nitrogen that can be either a purine (adenine, guanine) or a pyrimidine (cytosine, thymine, uracil).

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

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

These three components are linked together in a specific order to form a nucleotide. The phosphate group is attached to the 5' carbon of the sugar, while the nitrogenous base is attached to the 1' carbon of the sugar.