Short answers, pulled from the story.
Foreign policy is the set of strategies and actions a state uses in its interactions with other states, unions, and international entities. Governments develop foreign policy to pursue defense and security, advance economic interests such as trade agreements and foreign aid, and fulfill humanitarian responsibilities toward less powerful countries.
The term foreign affairs originated in 18th-century Europe, when fragmented and turbulent diplomacy led governments to manage international problems as isolated short-term issues called "affairs." The phrase remained in widespread use into the 20th century and still names several government departments that manage international relations today.
Smaller states have fewer economic and military resources, which limits their ability to exercise influence unilaterally. As a result, they tend to support international and multilateral organizations, seek alliances with larger countries, or avoid entanglement in international disputes to maintain friendly relations with all parties.
In democracies, public opinion and political representation both influence foreign policy, and democratic states are considered less likely to resort to military conflict with one another. Under dictatorships, foreign policy may depend heavily on the personal preferences of the ruler, making it less predictable and more prone to mistakes.
The responsibility to protect is a concept under which many states have developed humanitarian programs to assist less powerful countries. It is associated with liberal internationalism and the idealist school of thought, and support can take the form of defensive assistance, economic aid, or both.
The Council on Foreign Relations is based in the United States and Chatham House is based in the United Kingdom; both are among the leading institutions that study foreign policy. Think tanks like these are sometimes engaged by government foreign relations organizations to research proposals, develop policy alternatives, and assess evolving international relationships.