Just because you find an image on the Internet does not mean you have legal permission to use it in assigments or presentations. To find out whether you can use an image or not, look for usage guidelines on the site itself. And check out these resources on copyright as it relates to images.
Digital Images and Copyright: A brief guide to using digital images from the Internet made by Colgate University.
Copyright, Museums, and Licensing of Art Images: A guide from Columbia University Libraries on copyright, ownership, and the appropriate use of art images.
Copyright Court Cases: Summary of court cases on copyright by the American Library Association.
Stanford Copyright and Fair Use: Explanation and examples of fair use cases compiled by the Stanford University Libraries.
Visual Resource Association's Statement on Fair Use: This statement describes six uses of copyrighted still images that the VRA believes fall within the U.S. doctrine of fair use. The six uses are: 1) preservation (storing images for repeated use in a teaching context and transferring images to new formats); 2) use of images for teaching purposes; 3) use of images (both large, high-resolution images and thumbnails) on course websites and in other online study materials; 4) adaptations of images for teaching and classroom work by students; 5) sharing images among educational and cultural institutions to facilitate teaching and study; and 6) reproduction of images in theses and dissertations. This statment was written by VRA's Intellectual Property Rights Committee with the guidance of a Legal Advisory Committee of preeminent copyright scholars and legal experts.
Internet Image Searching Tutorial: Use this interactive tutorial to improve your image searching skills.
Like articles and other texts, images must be properly cited in papers. Your list of references may include but is not limited to:
Look at the following:
EasyBib: This free online bibliography maker will create citations for you in MLA, APA, Chicago/Turabian. Select 'digital image' or 'photograph' etc. from the 'All 59 options' tab and fill in as much information as possible.