What’s the difference between comments and information requests?

Although every submitted bug is carefully reviewed by a Team Leader before being forwarded to you, there is a chance you might need an extra piece of information from a tester to investigate a particular bug: browser version, Session ID, UDID, etc. If you want to get in touch with a tester, please use the Information Request Feature which you can find on the bar below in the bug detail view.
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Sometimes you are able to see the tester comment thread, but a dialogue does not start when you add a new comment. This means the tester or team leader will not be notified if you add a bug comment. This feature serves for documentation purposes only, which means bug comments, as well as attachments, get exported into your bug tracking system.