When to opt for .jpg, . png or .gif (It turns out it depends on what you're trying to capture - text, a still image or video/photos). Thanks once again, Amit Agwara!
"Pics4Learning is a copyright-friendly image library for teachers and students.... Unlike many Internet sites, permission has been granted for teachers and students to use all of the images donated to the Pics4Learning collection" (About Pics4Learning, 2008.09.03).