What are forum robot viewers under who's online?

They don't show up here but on another forum I'm on in addition to 'guests' and 'members' it also shows robots under who's on the forum currently.

Quote:

Robot: Google Viewing unknown page A moment ago Robot: Bing Viewing member profile Peutra A moment ago Robot: Yandex Viewing thread The Fall of Terrafel Discussion Thread A moment ago Robot: Baidu Viewing forum list 2 minutes ago Robot: Proximic Viewing members 6 minutes ago Robot: Brandwatch Viewing forum Mystery 8 minutes ago Robot: Google AdSense Viewing thread Self Publish? Yes. But why you choose it??? 14 minutes ago

So are they collecting advertiser data, are they search engines, or ????



I'd like to learn a bit more about them. Thanks.

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