I am crafting an application and cannot decide whether to use the terms Login/out or Logon/off. Is there a more correct option between these two? Should I use something else entirely (like "Sign on/off").
In terms of usability, as long as I am consistent it probably doesn't matter which terms I choose, but I did wonder about the origins of the terms - and whether one or another makes more grammatical sense. I also care deeply about the application I am creating, and want to take the time to investigate all aspects of its user experience.
Since you're looking for correctness,
login, logout, logon, and logoff are all nouns:
"Please enter your login credentials."
"I see three logons but only two logoffs from this user."
The corresponding verbs are each two words:
"Please log in to see your reputation."
"You must log off and talk to a human."
Update: according to dictionary.com, the various definitions of login are all nouns and involve gaining access to a computer or computer service. Interestingly, logon redirects to login as an exact equivalent. Have the definitions evolved?