If you have a lot of content to tag, you don't want to spend a lot of time adding tags one by one. Luckily, you can add tags to multiple entries and assets at once.
To tag multiple entries:
In the web app, click Content in the navigation bar.
From the list, select the entries you want to tag.
At the top of the list, click Add or remove tags.
In the editor, add or remove tags as desired.
Click Save when finished.
Tip: Use Ctrl + Z (Cmd + Z on Mac) to undo your changes.
Bulk editor: available on both on the content and media pages.
The bulk editor has a list of all tags on any of the selected entries or assets, along with a number showing how many of them contain each tag.
Click Apply to all to apply that tag to all selected entries or assets.
After clicking Apply to all, you will have the option to Undo, which ensures the tag will not be changed for any of the selected entries and assets.
Click the X next to the tag to remove it from all selected entries or assets.
You can also search for tags to add to all selected entries and assets in the bulk editor. Any tag added to your selection will be shown in orange, while removed tags will be displayed as a faded orange.