When you see an image, look for its Creative Commons license information. It will usually be visible when you open an image and will consist of words, small icons, or both.
In the case below, this image is licensed for Attribution and Share Alike. That means that it can be used provided that the copyright holder is acknowledged (Attribution) and that the user agrees to share any resulting works with the same license (Share Alike).
(Click on image to enlarge) Image: "Boxer_napping." Retrieved from: Fotopedia. <http://www.fotopedia.com/items/flickr-439504019>
Citing the images you use online is very important! You can get help from a librarian by visiting the library or using the librarian chat; however, below are some links to some sources that might help!
Select the APA or MLA tabs for information on citing images in papers and presentations.
Two seated figures and two-headed dog
within a circle, over bench decorated with figures and abstract elements. 1822. NYPL Digital Gallery. Web. 19 July 2010. <http://digitalgallery.nypl.org>.
Find images like this from the New York Public Library Digital Collection.