There are many resources available on the Internet. The websites listed below are only an example and not meant to be an exhaustive list. At the time of this writing all of the websites listed are currently active, however due to the transitory nature of the Internet; this may not be the case at any future date. Additionally, information from the Internet needs to be evaluated critically, with attention to origin, author, motive, bias, and age.
"Colorful science!" by Nat Sitticus/Flickr.com CC BY-NC-ND 2.0