Many people incorrectly assume that they have the right to use any image that they can find on the internet. For example, they may have done a quick Google image search to find a photo to accompany a blog post.
However, those images are still covered by copyright. Even though you can easily download them from the internet, you must secure permission to lawfully use them. It is not enough to simply list the source of the materials.
Don’t make the mistake of assuming it won’t be a big deal if you are caught. Copyright infringement can be expensive, and many photographers and stock image companies regularly perform searches to find unauthorized use of their images. That single image can end up costing you thousands of dollars.
Instead, consider finding a reputable stock image site, so you have a record of your authorization to use the images that accompany your blog posts.