When you're hunting for free images online, you'll encounter two terms constantly: Public Domain and CC0. Most people treat them as interchangeable. They're not — and the difference matters, especially if you're using images commercially.
What Is the Public Domain?
An image enters the public domain when its copyright expires, when it was created by a government employee as part of their official duties (in the US, federal government works are automatically public domain), or when the creator explicitly dedicated it to the public domain. In the United States, works published before 1928 are generally in the public domain. In most of Europe, copyright lasts 70 years after the creator's death.
The key thing to understand is that public domain is a legal status, not a licence. Nobody granted it — the copyright simply ran out, or never existed in the first place.
What Is CC0?
CC0 (pronounced "CC Zero") is a legal tool created by Creative Commons that allows creators to voluntarily waive all their copyright and related rights. When a creator applies CC0 to their work, they are saying: "I give up all rights to this. Do whatever you want with it, forever, worldwide, no strings attached."
CC0 is not a licence — it's a waiver. The distinction is subtle but important: a licence grants you permission to use something under certain conditions. A waiver removes the need for permission entirely.
Think of it this way: Public Domain means the copyright clock ran out. CC0 means the creator smashed the clock themselves.
Why Does the Difference Matter?
For most personal and creative uses, it doesn't matter at all — both mean you can use the image freely. But there are edge cases worth knowing about:
- Digitisation gotcha: Some institutions claim a new copyright on their high-resolution scans of public domain works. This is legally contested in the US (the Bridgeman Art Library v. Corel Corp case found that faithful reproductions of 2D public domain works cannot attract new copyright), but it's worth checking an institution's terms of service before using their scans commercially.
- CC0 is explicit: When you see a CC0 badge, the rights situation is unambiguous. The creator has gone out of their way to make it clear. Public domain status sometimes requires you to verify the copyright expiry date yourself.
- Moral rights: In some countries (particularly in Europe), creators retain "moral rights" even after assigning copyright — such as the right to be credited. CC0 attempts to waive these too, but some jurisdictions don't allow moral rights to be waived. Public domain works predate this issue entirely.
The Practical Takeaway
For the archives on this site, here's a quick guide to what you'll find:
- Library of Congress, NYPL: Mostly public domain by age. Check the "Rights & Access" section on each item.
- Smithsonian Open Access: Explicitly CC0. The Open Access badge means you're in the clear.
- Rijksmuseum: High-resolution downloads of their collection are CC0 — they were one of the first major museums to adopt this policy.
- Wikimedia Commons: Mixed. Each file has its own licence tag. Filter by "CC0" or "Public Domain" using the licence filter on the search results page.
- Pixabay, Unsplash, Pexels: Their own licences — generally very permissive, but read the terms for commercial use.