Galactic Standard Credits are the most widely accepted currency in the galaxy, and are used for all major interstellar transactions.

Barter is not a major economic system used in interstellar trade, as it is too inefficient and time-consuming for large-scale transactions.

Starships are the primary mode of transportation used for interstellar trade, as they are capable of traveling long distances and carrying large amounts of cargo.

Cultural preferences are not a major factor that affects the price of goods in interstellar trade, as they are not universal and can vary greatly from one culture to another.

Interstellar Economic Union is the term used to describe the economic relationship between two or more planets or civilizations that are engaged in interstellar trade.

Asteroid Belts are not a major type of interstellar trade route, as they are too dangerous and difficult to navigate.

Interstellar Commerce is the term used to describe the process of buying and selling goods and services between different planets or civilizations.

Manufactured Goods are not a major type of interstellar trade commodity, as they are too expensive and time-consuming to produce.

Socialism is the economic system in which the means of production are owned and controlled by the government.

Common Market is not a major type of interstellar trade agreement, as it is too difficult to implement and enforce.

Capitalism is the economic system in which the means of production are owned and controlled by private individuals or corporations.

Subsidies are not a major type of interstellar trade barrier, as they are too expensive and difficult to implement.

Communism is the economic system in which the means of production are owned and controlled by the workers.

World Trade Organization is not a major type of interstellar trade organization, as it is too Earth-centric.

Mercantilism is the economic system in which the government intervenes in the economy to promote economic growth and stability.