Diplomacy is relationship-building between representatives of countries and states to further one country's interests with another. Diplomacy involves speaking, negotiating, and working with the other parties involved to resolve geopolitical issues and advance a country's interests.
The head of the diplomacy team is called a diplomat. The head diplomat is often the one with the most experience in dealing with skilled adversaries. One of the key parts of successful diplomacy is to conduct negotiations and maintain good relations while being firm and not arousing hostility in the other party.