sentences:  To "sign in" connotes the same idea, but it's based on the analogy of manually signing a log book or visitors book.While there is no agreed difference in meaning between the three terms ("login", "logon" and "sign"-"in"), different technical communities tend to prefer one over another – Unix, Novell, Linux and Apple typically use "login", and Apple's style guide says ""Users log in to a file server (not log on to)...".