Description of a set based on a list of its elements.

In general, the extensional definition of a set provides a list of all the elements in the set. When the set is not finite but includes a provisional set of elements, then we use an ellipsis to indicate that the list continues like it started.

### Example

- The set V of vowels in the English alphabet: V = {a, e, i, o, u, y}
- The set L of letters in the Latin alphabet: L = {a, b, c d, e, f, … , x, y, z}
- The set of whole numbers: \(\mathbb{W}\) = {0, 1, 2, 3, 4, 5, 6, 7, …}.