A treaty is a formal, written agreement between sovereign states or between states and international organizations. In the United States, treaties are negotiated through the executive branch, which includes the Department of State. Once the negotiators have accepted the terms of the treaty, the president sends the treaty to the U.S. Senate for its “advice and consent” on ratification, or endorsement. If the Senate agrees that the president should ratify the treaty, it goes back to him/her and s/he ratifies the treaty with his/her signature.
The subjects of treaties span the whole spectrum of international relations: peace, trade, independence, reparations, territorial boundaries, human rights, immigration, and many others. As times change, so do treaties. In 1796, the United States entered into the Treaty with Tripoli to protect American citizens from kidnapping and ransom by pirates in the Mediterranean Sea. In 2001, the United States agreed to a treaty on cybercrime. Source: United States Diplomacy Center
Embassies help American citizens in many ways. The effects of some are in plain sight, issuance of visas to promote international visits to the United States while maintaining our border security. Other effects are less obvious but can have an even more direct impact: a trade agreement worked out at the U.S. embassy in Japan, for example, might well affect you personally in the lower cost of a car, but you would probably never know it. Close consultations with foreign governments and international organizations can stop an illness from becoming a pandemic. Skillful negotiations can prevent a small conflict from spiraling into a war.
While the Consular officers provide immediate and personal assistance to American citizens every day around the world -- replacing lost passports, assisting injured or ill travelers, and assisting with marriages, births, and adoptions, other sections of the embassy provide more specialized assistance. The Foreign Commercial Service or Foreign Agricultural Service helps American businesses connect with local counterparts to increase American exports. The economic section works with local political leaders to ensure that finance laws and regulations remain friendly for American businesses. The public affairs section presents U.S. policy, values and culture to local media and public and helps visiting American journalists get background, official interviews, and information for their stories. The U.S. Agency for International Development works with host country institutions to encourage agrarian and business enterprise and to enhance infrastructure. Military attaches and drug and law enforcement agents manage programs and conduct exercises which create better coordination between army and police services. Source: U.S. Diplomacy Center