Logging in or on?

There are a plethora of words for user accounts, like logon, login, signon, and also the action of logging in (or logging on) or signing in.

Are there any usage guidelines here?

I found some infomation on Stackoverflow.

This is particularly useful:

login, logout, logon, and logoff are nouns or adjectives

log in, log out, log on, log off are verbs

for developers, this will probably be helpful in deciding which term to use:

Just an observation, but the more casual the site, the more likely it’s going to use Sign in/Sign out. The paradigm of a visitor making an announcement of presence to a casual gathering of people. More formal sites tend to want you to Log in and Log out. The wording suggests the clocking in for work; The paradigm of a person with an accredited level of authentication accessing a secure terminal and leaving a record of that visit in a log.

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