This document discusses tariff and non-tariff barriers to international trade. It defines tariffs as taxes imposed on goods crossing national borders and notes that they are used to protect domestic industries by making imported goods more expensive. It also discusses different types of tariffs and their impacts. Non-tariff barriers are other restrictions beyond tariffs that limit imports or distort trade, such as quotas, import licensing, and customs procedures. Both tariff and non-tariff barriers can impact trade volumes, inflation, and international relations.