Question about the website?

Okay,
When I get on line and look to the friendly box ( what members are on line) to the right of my screen, it shows my name and many others in blue.
Some are in Black and every so often one or two in red.
what does the color designation mean?

Also, at the bottom of the same box shows how many people are on line and how many "bots."
What the heck is a "bot?"
What do the "bots" do while they are on line?

Thanks,
Joe