It’s a bit of a jungle out there, also when it comes to different licenses of both free and purchased images. If you look for photos and films with a CC0 license (Creative Commons zero license) you can be sure that you won’t have a long list of demands and requirements. CC0 equals ‘No rights reserved’.
A Creative Commons CC0 license means that:
‘The person who associated a work with this deed has dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.’
You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
In no way are the patent or trademark rights of any person affected by CC0, nor are the rights that other persons may have in the work or in how the work is used, such as publicity or privacy rights.
Unless expressly stated otherwise, the person who associated a work with this deed makes no warranties about the work, and disclaims liability for all uses of the work, to the fullest extent permitted by applicable law.
When using or citing the work, you should not imply endorsement by the author or the affirmer.
There are many other types of licenses. But the most common ones that you may come across are Royalty-Free and Rights-Managed. Both of those comes with a lot of requirements and restrictions. So try to avoid them unless you really have no choice.