You hit "publish."
Later, a photographer contacts you and informs you that you need to take down the image, because it's his. You apologize, remove the image from your blog, and think that's the end of the matter. It's not. For blogger Roni Lauren, it was the start of an odyssey involving lawyers, money, and a whole lot of headache.
PUBLIC DOMAIN
It's free for anyone to use for any purpose. There is no copyright protection on this work.
CREATIVE COMMONS
It's free to use with certain conditions. You may be required to credit the source, link back to the original source, use only for non-commercial purposes, etc. See an overview of the licenses here.
FAQ
What if I put a disclaimer on my website?
[My blog] claims no credit for any images posted on this site unless otherwise noted. Images on this blog are copyright to its respectful owners. If there is an image appearing on this blog that belongs to you and do not wish for it appear on this site, please email with a link to said image and it will be promptly removed.
What if I use an image for non-commercial purposes?
What if I link to and credit the source?
What if I filter Google Images by copyright?
Don't trust the filter. It may be a good way to find an image you like, then look into it to make sure that it's safe to use. But when in doubt--skip it!
Can I use an image from Pinterest or Tumblr?
Can I use an image from Flickr?
Can I use an image from Wikipedia Commons?
How do I know if an image is safe to use?
P.S. Like I said above, go to my blog post that lists Websites with Free Images for Bloggers to find great sources of images for your projects.