ELI5: Explain Like I'm 5

United Kingdom–Crown Dependencies Customs Union

The United Kingdom and the Crown Dependencies (which includes Jersey, Guernsey, Isle of Man and Gibraltar) have a special agreement that allows people, goods and services to move freely between them. This is known as a 'Customs Union'. A Customs Union means that there are no extra taxes or charges on the goods and services moving between the UK and the Crown Dependencies and all crossings into and out of the Dependencies are treated as if they were within the UK. This makes it easier and cheaper to move goods, people and services between the UK and the Crown Dependencies.