What is well definent set give 5 examples?

A well-defined set is a collection of distinct objects or elements that can be clearly identified and have a specific membership criterion. This means that for any given object, it can be definitively determined whether it belongs to the set or not.

Examples of well-defined sets include:

1. The set of all even numbers.
2. The set of prime numbers less than 20.
3. The set of planets in our solar system.
4. The set of all U.S. states.
5. The set of all vowels in the English alphabet.