Wearing my WordPress developer hat (metaphorically speaking) I’ve always told clients to log in to their websites using the form of address:
That’s because that’s the actual name of the folder that contains the admin area physically on the web server.
I was surprised to find that WordPress (on the quiet) actually always put a redirect in place so you can make things easier to remember (and save typing 3 letters!) by just going to:
I’ve been using WordPress for years – it’s amazing what you can stumble over from time to time.