The United States Department of State (DOS), often called the State Department, is the federal executive department that advises the President and conducts international relations for the United States. In 1789 it was the first executive department to be established by the United States. The most similar thing other countries have is a "Ministry of Foreign Affairs", but no other countries separates the powers like the U.S. government, so it's quite unique.
Aside from the Department of State's international relations role and implementing the foreign policy of the Executive Branch (US President), it also provides services to U.S. citizens traveling abroad and to foreigners visiting the United States:
- Issuing passports and travel advisories
- Ensuring protection of and aiding all U.S. citizens living or traveling abroad
- Providing assistance to U.S. businesses operating internationally
- Informing the public about U.S. foreign policy and relations with other countries