At an event in Singapore yesterday, Seamus Byrne, the editor of CNet Australia, tweeted that 50% of Facebook's 900 million users login in every day.

He followed that up with a tweet saying that 500M use Facebook mobile.

I did a doubletake at that point.

It wasn't Seamus' data, so no slight on him, but what does it even mean to log in when we have apps that grab every new scrap of information? Do I login to Gmail 200 times a day, just because I get each new email pushed at me? (Yes, I get a lot of mail.)

Similarly, if every one of those Facebook mobile users has an app that checks for content regularly, then does that count as a login? If so, 500M Facebook mobile automated updates accounts for the more than 500M that log in every day. What if those people never actually open the app?

Facebook has persistent login that tracks you around the web, telling you which of your friends has "liked" that puppy picture you just saw on imgur.com. Does that count as a login? Even if you haven't visited Facebook.com today? What if you like the puppy pic?

It feels as though "login" should describe a meaningful, active step. Not automated, (although, of course, we all want to automate our meaningful and active logins), not notifications, and not web reminders that are the smoke-trail of a login that hasn't been meaningfully and actively logged out.

Maybe it's just me, but the behaviour I expect of a site I register for and log into is something along the lines of: check my browser for automated login when I head to your site, then auto time-out my login once I navigate away for a period of time (say 15 mins). Rinse, repeat. Sure, that may register five logins a day for me at facebook.com, but that's a measure of my intent and return to a site. I'm sure Facebook measures that anyway... but you get my point, I hope. My intuitive sense of a login derives from action on my part.

What behaviour do I expect from a phone? The notion of a login seems harder to pin down.

Checking notifications on, for example, Facebook Messenger, doesn't feel like a Facebook login to me. Even though, were I on the web, I'd have to go to facebook.com to view those messages.

That's because the Facebook Messenger app only taps into a tiny portion of my Facebook experience, and to me, it doesn't feel like a login unless I can access the full service. The Facebook app, on the other hand, feels like a login. Not when it has a notification pending, but only when I open the app to read that notification.

What actually happens with your phone is that when you launch the app it will log in in order to pull data down. After that, it will keep updating, without logging you out and back in, until you close the app. If you run the app in the background, it may not log out until the session times out - essentially, a site may say "after you've been logged in for five days, you have to log out and back in so we know you still really mean it.."

In other words, the user understanding of a login, and the developer understanding of a login, are vastly different.

Initially, the user understanding and the developer understanding of a "login" was identical. The user typed in a username, and then a password, if needed, to access a site, software, or whatever. When they were done, they logged out.

But over time, and as Web 2.0 and now mobile web has come to dominate, the user understanding of a login has become so divorced from the developer concept of a login that it doesn't really tell us much to say that a "site" has "logins".

Heck, I'm even using scarequotes for "site" now, because really, what's our understanding of a "site"? Does it depend what the meaning of "is" is?

I'm going to go contemplate my navel now.