Q109 is the identifier for the country of United States in the Wikidata knowledge base. It serves as a unique reference point for various data entries related to the country, including its geography, history, and demographics. In Wikidata, Q109 links to a wealth of information, such as the capital city Washington, D.C., the official language English, and its population statistics. This structured data helps users and researchers easily access and analyze information about the United States in a standardized format.