International trade is the exchange of capital, goods, and services across international borders or territories because there is a need or want of goods or services.
In most countries, such trade represents a significant share of gross domestic product (GDP). While international trade has existed throughout history (for example Uttarapatha, Silk Road, Amber Road, salt roads), its economic, social, and political importance has been on the rise in recent centuries.
An economic union is a type of trade bloc which is composed of a common market with a customs union. The participant countries have both common policies on product regulation, freedom of movement of goods, services and the factors of production (capital and labour) as well as a common external trade policy. When an economic union involves unifying currency, it becomes an economic and monetary union.
The purposes for establishing an economic union normally include increasing economic efficiency and establishing closer political and cultural ties between the member countries.
A customs and monetary union is a type of trade bloc which is composed of a customs union and a currency union. The participant countries have both common external trade policy and share a single currency.
Customs and monetary union is established through trade pact.