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

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

3. A phosphate group: This is a group of one phosphorus atom and four oxygen atoms.

These three components are linked together in a specific way: the nitrogenous base is attached to the sugar, and the phosphate group is attached to the sugar.

Here's a simplified way to remember it: Base + Sugar + Phosphate = Nucleotide