Free photo-sharing sites

There are many different free photo-sharing sites on the web. This 2007 article from the N.Y. Times by David Pogue compares 8 of them. 
 Find images on Google that you can reuse – Google Support article 
 Some major sites: 
 
 Flickr 	 500px 	 Imgur 	 Photobucket 	 Instagram 	 Imageshack 
 
 
 
 Free Stock Photos: 74 Best Sites To Find Awesome Free Images – Feb. 5, 2015 	 
 The Ultimate List of Completely Free Images: 43 Handpicked Services – March 8, 2015