Fostering a box allows you to receive notifications about the box such as find and attempt reports (including both public and private comments). You cannot edit the box itself, but you will have access to add or edit an “addendum” which will show up on the box details page as well as AQ-hosted clues. If there's information about the box that people should know like the clue has changed or needs maintenance, this is where you can tell others about it.

Boxes become available for fostering if the owner hasn't logged into AQ for some time and the listing becomes abandoned. Anyone can foster a box, but boxes can only have one foster parent at a time. If the owner of the box later logs back into AQ, you'll lose your fostering status. If a box is available to foster, you'll see an option to foster the box on the box details page.