Is there accepted terminology for the process of logging in?
As a verb, would you say "Go to the website and log in", or "Go to the website and login"?
As an adjective, would you say "Click on the Log in form", or "Click on the Login form"?
Does the same apply to logging out? eg: logout?
Well the other option (so there is something to vote on) is log in and log out. (I'm not going to vote for my reply).
Google can be useful :)
Results 1 - 10 of about 1,690,000,000 for login
Results 1 - 10 of about 338,000,000 for "log in"
Edit re comment
Results 1 - 10 of about 2,100,000 for "login to the site"
Results 1 - 10 of about 371,000 for "log in to the site"
I think Google can usefully show where the use of language is changing.
I think that they're totally separate terms. You "log in" to a system, whereas your "login" refers to the credentials which you use to "log in" with.
login as a noun or adjective: login prompt, login screen, etc.
log in as a verb: I'm going to log in now.
Same idea with logout: You can log out by clicking on the logout button.
"Login" is not a verb. When you want a verb the proper english is to use "log in."
i.e. "Please click here to log in"
I would use it as a noun, such as "The login form is on the right"
But is it not a verb.
To add to what everyone's saying: compound words follow this pattern in English pretty generally. You log in via a login screen. You lay out a layout. You set up a setup. There are some words that smush together as both verb and noun (you download a download), but I can't think of any that go the other way.
You don't even need to think about the grammar to know that login, setup, and backup aren't verbs. If you have a reasonably firm grasp of the language, you can just "feel" that they're wrong.
My preferences (less popular, but many cool websites are using this convention):
[Sign In] [Join]
Welcome, UserName! [Sign Out]
I wouldn't use any of the following: Log On, Logon, Log In, Log Out
Another option is (which is by the way more popular):
[Login] [Register]
Welcome, UserName! [Logout]
Google Stats (hits):
[Sign In], [Sign Out] -> 1 210 000 000 + 300 700 000 = 1 510 700 000
[Login], [Logout] -> 1 940 000 000 + 88 200 000 = 2 028 200 000
[Log In], [Log Out] -> 873 000 000 + 83 800 000 = 956 800 000
[Sign Up] for registration link is also a good option but it does't look good near [Sign In], you should use it wether with [Login] or seporatly.
[Sign In] [Join] on a page looks more user-friendly (less official) for me than [Login] [Register]
The Yahoo style guide states:
login (n., adj.); log in, log in to (v.)
One word when used as a noun or an adjective. Two words when used as a verb, which may be followed by the preposition to. Note that sign in is preferred because it sounds less technical.logoff (n., adj.), log off (v.)
One word when used as a noun or adjective. Two words when used as a verb. Note that sign out is preferred because it sounds less technical.logon (n., adj.); log on, log on to (v.)
One word when used as a noun or adjective. Two words when used as a verb, which may be followed by the preposition to. Note that sign in is preferred because it sounds less technical. Don’t use log on to mean simply visiting a website.logout (n., adj.), log out (v.)
One word when used as a noun or adjective. Two words when used as a verb. Note that sign out is preferred because it sounds less technical. Example: If you forget to log out, you’ll get a logout reminder.