What is the UK ETA?
The UK Electronic Travel Authorisation (ETA) is a pre-travel permission introduced by the United Kingdom for visitors from eligible countries — including the United States — who previously could travel to Britain without any prior authorisation.
The UK ETA is not a visa. It is an automated electronic check linked to your US passport that must be obtained before you travel. It does not guarantee entry — UK Border Force retains the right to refuse admission on arrival — but it is a mandatory requirement to board any flight or ferry to the United Kingdom.
Once approved, your ETA is valid for multiple trips over two years or until your passport expires, whichever comes first.