Part of macOS

`cloudphotod`iCloud Photos

○ Leave it

Uploads and downloads your photos with iCloud.

What it is

Keeps your Photos library in step with iCloud Photos.

Why it might be busy

After taking or importing many photos. Usually until syncing finishes.

If you stop it

macOS starts it again straight away. Leave it.

○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.

From Procession’s guide, in the words the app shows.