Sessions the snippet recorded but could not attach to a person, because nobody was signed in.
One Row Is One Browser
Unlike Identified Users, rows here are one browser profile each. The same human on a laptop and a phone is two rows, because there is nothing to merge them on.
What This List Is Actually For
It answers *how much traffic have I not identified yet*. That makes it a diagnostic as much as a list: a large anonymous count next to an empty identified count usually means the snippet is on your marketing pages but not on your signed-in ones.
Anonymous sessions have no contact information by definition, so the Has contact info filter section is hidden on this list rather than shown returning nothing.
Access to the anonymous list is a paid-plan feature.