How do you say it? which one is right? Have you ever wondered how you should write this when you're talking about the process of authenticating yourself against a system? Do you write: "I'm going to login to the accounting system" or "I am going to log in to the accounting system." I mean its easy to mumble through it, or say it fast enough or with confidence so it just sounds right. People do this all the time, but really, most can't spell it properly in each case, or rather, can't differentiate between the two, primarily because they don't know there's a difference, enough commas don't you think? Lets move on...
I had a great idea of finding the real truth about this for you, but someone beat me to it! The nerve! to top it off they explain it much better than I could have ever done it. So here it is, remember this one for the future and make sure you use it properly.
By a guy identified as semicolon, at everything2
[continued] ...Since I have no willpower, I did end up logging in, but not before taking a moment to ponder the word login. It seemed out of place where it was. I've always thought of login to be a noun and log in to be the verb. The logic behind this, I suppose, is that in log in, log is the verb and in is where you're logging, and login is just some word a guy in thick glasses made up for the thing people are supposed to type when they are logging in (i.e., "Please type your login and password in the boxes below."). Turns out I'm pretty much... [continue]
So that's the difference between log in and login. "log in" is the act of "logging in" while login is a thing, your username, or other id that goes alogn with a password.