How to apply for a UK ETA involves completing an online application for the Electronic Travel Authorisation required to enter the United Kingdom. Applicants must provide passport details, personal information, travel plans, and answer security questions. The process is usually done through the official UK ETA application system using a smartphone app or online portal. A digital photograph and payment of the application fee are required. Most decisions are made quickly, often within minutes to a few days, but travellers should apply in advance. Once approved, the ETA is electronically linked to the passport and used for multiple short visits. It does not guarantee entry at the border.