What does the chat box mean on Facebook?

[Mochi the Great]

When you are on your news feed, to the left there are tiny boxes of people's profile pictures. Sometimes there's a tiny green dot on them to let you know that person is on line and sometimes it's just the picture alone. When it is just the picture and no green dot, what does that mean?

[SteveO]

It means that they're not online.

[Will]

It means they're offline, but still shown because it has a phone picture next to it, saying they're on their phone. Or it just might be a Facebook error that happens to everybody.

[$UN!QUE$]

green means online
orange means busy
no dot? offline
phone then either they are on phone or they had been on phone some 2-3 hours earlier

[Angeleyes]

When it shows just the picture and no green dot it means they are offline.