UPDATE: We've recently communicated changes to Marketplace that go into effect June 30th, 2018. For more details regarding these changes and how they may affect you, please visit our Marketplace Transition FAQ.
In order for a photo to be used for commercial purposes, it must pass certain legal and content guidelines. Photos available for commercial use must have model releases for any recognizable people in them, and can't contain any trademarks or logos, for example.
We also have an extensive collection of photos available for Editorial Use, which doesn't have to follow the same guidelines as commercial photos. Editorial only photos are used as an effective way to strengthen newspaper and magazine articles, blog posts, and other written commentaries, by lending visual context to a story.
All photos on the 500px Marketplace are approved for editorial usage, as our standard license agreement includes it along with commercial use. However, some photos are available only for editorial usage.
You'll see this notice on editorial only photos.