Chat icons on facebook what do they mean?

I am aware green suggests online but if they the grey one imply
Like if its on for an hour or so or so but isn’t going to change POST sent an individual message ( possibly not through chat) and no response one hour later her icon was still dull then your lady disappeared.

Does it show this way if another person is playing a personal game or looking around facebook
Or can it be only when they walk from the computer

It signifies they’re idle or they might be in their cell phone device.Should you keep squidoo pulled up, but arent utilizing it, it’s going to go in “idle” method, giving everyone the grey dot.