The bots. (What are they anyway?)

When I view who is online, I see google bots bing bots and more. What do they do?
Game Editor discussion board
http://game-editor.com/forum/
MrJolteon wrote:Search engine stuff.
jonathang wrote:Yeah, I find the bots a bit annoying. I once thought: Yay 5 people online!![]()
I just noticed that 4 of them were bots and one of them was me.