I've seen similar questions like this on the site before, but was wondering if anyone was able to point me to an official site that says that, as an American citizen traveling to the UK, the stamp put on my passport at the airport is an entry stamp and does NOT count as a visa. Or, alternatively, a site that says the opposite. Or has any real information about this, to be honest, I'm getting a bit desperate!
I know as an American citizen I do not need a visa to get into the UK as a tourist, but I need to know if the entry stamp counts as a visa given at the airport. Basically, if you enter the UK for a short-term visit (just to see the country), are you given a visa at the airport?