With the flag function you can mark, unmark or reject an item.
This is useful when you look through a large number of newly imported images in full screen view and pre-select the photos you want to keep for further processing and which may possibly can be deleted. This has the advantage that the rejected images are not deleted physically, but are intended for deletion. In a second pass, you could again review only the rejected images and then finally decide whether they can really be deleted or remained in the catalog.
On the Thumbnail preview the checkbox for flagging is located to the bottom right below.
Flagged Rejected Unflagged
Flagging with a Mouse
Flag – If you click once on the box, then it is flagged and the color changes to green.
Unflag – If you click it again, then the flag is canceled.
Reject – If you hold down the Ctrl key and click the image. It will be marked as rejected symbolized by the red coloring.
Flagging with the Keyboard
Press [f] key for flagging
Press [u] key for unflag
Press [x] key for rejecting
In the Catalog Tags Panel on the left side you can see the quantity of all flagged, unflagged and rejected images.
In the Properties panel on the right side you will find the Flag tag under the System tab.