Travellers planning to visit the United Kingdom should prepare the required documents and understand the conditions before applying for an Electronic Travel Authorisation (ETA). The complete UK ETA requirements guide explains the essential documents and basic application conditions. Applicants need a clear scan of their physical passport bio page, with all four corners and the MRZ code visible. They must also provide a recent colour passport-size photograph taken within the last three months against a plain light background. The passport must remain valid throughout the intended stay. Travel should be for an eligible purpose, and each traveller, including children, needs an individual ETA. Applicants should also ensure their UK stay does not exceed six months per visit and review all requirements before submitting their application.