This means that we really like it! When our team moderates images, we also mark images that we think are exceptional with a star! We always email you when you’ve got new starred images on your profile, but usually, it takes one working day for this email to arrive.
If you're a photographer using our FTP service, our system works slightly differently, you can read more about it here.
You can see whether an image has been starred underneath the image on each pic page:
You can also choose to view all starred images from one photographer on their profile page: