You should always cite or attribute any images you use. Check out this handout for an introduction to image citation and attribution.
Trinacria, etching, aquatint, soft-ground etching, mm. 665x425, Engraved and designed by Toni Pecoraro. Image via the Wikimedia Commons.
Need images? Your best bet is to start with ARTstor, a database with over 2.5 million images on a variety of subjects. Be sure to check out their Youtube Channel for helpful videos on setting up a user account, downloading images to PowerPoint, and more!
Bridgeman Education is another great image database for finding images of art and architecture. Search or browse to find images. You can also export images to PowerPoint for easy presentations