I was just running FxCop and it has complained that I used the term "Log In" instead of "Log On", but I am sure this is wrong. My search around the internet shows that people use all of the following, but I cannot decide which one is best:

  • Log In
  • Login
  • Log On
  • Logon
  • Sign In

The only thing that we agree on here is that whichever one you use the Log In term should match the Log Out term (IN-OUT ON-OFF etc).

What do you think? Should we use Sign or Log, In or Out, one joined up word or two separate ones?


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]


I would argue the one word form is the noun - e.g. you have a Login for a system - and two words is the verb form - e.g. you Sign in to the application.

I prefer Sign In/Out as the Log can refer to Log files only and not user authentication.


A quick Google statistics shows:

login    - 1.940.000.000 hits 
sign in  - hits
log in   -   993.000.000 hits
logon    -    29.000.000 hits
log on   -    26.900.000 hits

I always use 'ON' with 'OFF', same for 'IN' and 'OUT'. You also say "Single Sign On" so I was under the impression that it's "Sign On/Off".

My personal preference is the same: "Log In/Out" and "Sign On/Off".


Microsoft published a book, Microsoft Manual of Style for Technical Publications that covers exactly this subject. They indeed made LogOn a standard, mainly because of inconsistencies in the .NET framework itself.

The FxCop rule is probably based on the suggestions in this book. Of course, these are only recommendations, and I doubt it matters which one you actually choose. If you want to follow MS in this, then just use LogOn. If you prefer something else, just edit the CustomDictionary.xml in FxCop, and be done.


Looking at stack overflow for comparison, they use:

Login & Logout


There is also "Sing Up". Anyone knows the opposite? Sing off, sign away, sign out or how?


According to wikipedia you

'login' and you 'log out'


but the important this is that throughout your system you use the SAME term. Dont mix 'log in' and 'login'


This is a repeat of a previous question: http://stackoverflow.com/questions/307528/login-or-log-in