UK ETA: THE NEW TRAVEL RULE
The UK is introducing the Electronic Travel Authorization (ETA) system, a significant change to its border and immigration framework. If you’re from a visa-exempt country (but not the UK or Ireland), you’ll soon need to apply online before you set off. Similar to the US ESTA or Canada’s eTA, you will need to apply online prior to your journey. Visit:
https://www.gov.uk/guidance/apply-for-an-electronic-travel-authorisation-eta#who-can-apply
Get the App.
https://apps.apple.com/us/app/uk-eta/id6444912481
https://play.google.com/store/apps/details?id=uk.gov.HomeOffice.ho3
Your ETA lasts for 2 years. You can travel to the UK as many times as you want during that time.