The stock rules will vary according to subject depicted in the image. Please note that in the description of each image the rules should be stated, but here is a quick overview.
Non-human organisms and non-living objects:
Free for use and with full permission, commercial or private. No credit needed or permission.
Model stock is currently unavailable, however, this stock will require a link back and a quick comment. Any commercial uses require permission before use.
Please be wary between what is stock and what isn't. Any deviations found violating these rules will first be noted to remove it and if that doesn't happen the deviation will be reported.
Please feel free to leave a link to wherever the stock is used so I can see!