I wrote in my Old Usernames article about the importance of Twitter’s User ID in keeping tabs on slippery people’s behaviour. The User ID is a unique account identifier which remains the same however many times the user changes his or her @username. If you know the User ID, you will always be able to find a given Twitter profile (or at least find what’s happened to it) via its numerical URL.
But what happens if you discover that, say, a group of account @usernames have been switched, and you need to actually prove that the switch has taken place? This can happen with account networks when they try to cloak their origins. And it became important recently when the lead profile in a network of raving political activist accounts rebranded as the main promo feed for an alternative social media platform claiming to be politically impartial. I know, you couldn’t make it up, could you?
Well, there is fiendishly clever way to find out who’s been switching usernames, and PROVE it. Anyone can do it, and you can read the full tutorial in: How To Retrospectively Find a Twitter ID Number.