Simple Definition:

Introvert is a term used to describe a person who prefers to spend time alone and finds social interaction draining.

Examples:

• Sarah is an introvert, so she enjoys reading books in her room rather than going to parties.
• David is an introvert, so he feels exhausted after attending a large gathering with lots of people.

Very Simple Definition:

Introvert means someone who likes being alone and gets tired from being around others.

Examples:

• Sarah likes being by herself, so she reads books alone. She is an introvert.
• David is an introvert. He feels very tired after being at a big party.