There are many different types of usage licenses for photos and it’s important to understand the differences between them so you don’t accidentally use a photo incorrectly.
Remember, using a photo that is technically “legal” to use in the WRONG way is just as bad in the eyes of the courts a using a photo illegally. Either way is infringement on the photographer’s rights.
Public domain images are either issued deliberately into the public domain, or they are so old that the original copyright has expired.
There are archives that specialize in providing searchable databases of public domain photos, so it’s pretty easy to find them just by searching such sites.
Photos that are in the public domain can be used for an purpose, non-commercial or commercial, without payment.
Creative Commons actually has several different type of licenses, and how you can use a particular Creative Common photo depends on which license it’s been issued under.
Creative Commons 0 (Zero, or CC0) is basically the same as public domain. A CC0 image can be used for anything you want, and no payment or attribution is required.
The other licenses are a little more restrictive. Some d not allow commercial use. Others require attribution.
You can read more about Creative Commons licenses here:
Always check the license of a particular Creative Commons photo before you use it to be sure you’re following the terms of the license
Royalty free licenses don’t give you the right to use a photo for FREE (unless specified). Instead, they give you the right to use the photo without ongoing royalties.
Royalties are monies paid out for continuing use of a particular work, such as a photo, song, or video. For example, musicians are often given payment for sales o their music for many years after the music is recorded.
With royalty free photos, you don’t have to pay the photographer a fee every time someone accesses the website you use it on, or every time someone buys the book you used the image on the cover of.
Royalty free licenses can vary widely from company t company, so it’s important you read the license at each site you buy from carefully to make sure you understand them.
Some things to note with regards to royalty free licenses:
Some licenses require you to pay an extra fee if you us an image for a book cover and sell more than a certain number of copies (for example, 250,000).
Some (most) licenses require you to buy an extended license for certain uses, such as printed items like t-shirts or posters, or for use in a logo.
Some licenses forbid certain uses, such as use in works that promote hate or violence, or in works that may be considered pornographic.
Always read licenses carefully!