The UK ETA (Electronic Travel Authorisation) requirements apply to travelers who are eligible to enter the United Kingdom without a visa. Applicants must hold a valid biometric passport from an eligible country. They need to provide personal details, passport information, and contact details during the application process. A recent facial image or selfie may be required for identity verification. Applicants must also answer security and eligibility questions related to criminal history and immigration compliance. A small application fee is required, paid online. The ETA is mandatory before travel and must be approved before boarding a flight to the UK.