On my site, you can find two types of images – images released under creative commons license and royalty free images.
For my creative commons images, I use the Attribution-NonCommercial 4.0 International license, which means that you can use these images for free for non-commercial purposes if you credit me as an author. I would also appreciate a link to this website:)
Royalty free images are images that you have to license either through their author or through professional micro-stock agency. You have to buy a license to be able to use the image; royalty free means, that once you buy a license, you can continually use and profit from the use of the image without paying its author additional royalties.
This is a list of agencies, where I currently offer my royalty free illustrations:
List of agencies I’ve formerly contributed to: