A UK ETA is an electronic travel authorisation for eligible visitors who do not need a visa to travel to the UK.
It is generally used for short visits of up to 6 months, such as tourism, visiting family or friends, or certain permitted short-term purposes.
However, a UK ETA does not guarantee entry to the UK; final permission to enter is decided at the UK border.
A visa, on the other hand, is a formal entry clearance that may be required depending on your nationality, purpose of travel, or length of stay.
You may need a visa if you plan to work, study long-term, get married, stay longer than permitted under an ETA, or visit the UK for a purpose not covered by ETA rules.
Travellers should check in advance whether they need a UK ETA or a visa before travelling.