Tagging or deleting multiple cards at once (bulk editing cards)

Desktop

To tag or delete multiple cards at one time, just hold SHIFT and select the cards you'd like to change. 

A bar will appear at the top of your screen where you can delete all selected cards at once, add them to space or enter your desired tags.

Mobile (iOS v4+ only)

Long-press any card to activate bulk-edit mode. You can then select as many cards as you like from your Everything view or in a Space. You can then tag them all, add them all to a Space, or delete them.

With only one card selected, you can add it to your Top of Mind.