Simplify the following text for a Grade 10 native English-speaking person.
Original: Puerto Rico ( or ) , officially the Commonwealth of Puerto Rico ( , â '' literally Associated Free State of Puerto Rico ) , is an unincorporated territory of the United States , located in the northeastern Caribbean Sea , east of the Dominican Republic and west of the Virgin Islands .
Simplified: Puerto Rico , also known as the Commonwealth of Puerto Rico , is a territory or colony of the United States in the Caribbean Sea .