Yes, a US citizen does not need a visa to travel to London for stays up to 6 months.
Yes, American citizens do not need a visa to travel to London for short visits, typically up to 6 months.
Yes, Colombians need a visa to travel to London.
Yes, US citizens need a visa to travel to London.
Yes, a US citizen needs a visa to travel to Russia.
Yes, an Indian citizen needs a visa to travel to Jamaica.
Passport and airline ticket that's it. Before you land British authorities will have you fill out a form asking you how long you will be in the country, where you are going, and why you are there. It is pretty simple to do.
No, you do not need a visa.
Yes, a European citizen needs a visa to travel to the USA, unless they are eligible for the Visa Waiver Program.
NO
No
No
Yes, a visa is required.