The definition of what is "pornographic" varies quite a bit between different countries. In some (the USA, for example), practically all forms of nudity are illegal. In others, nudist pictures or art pictures with nude kids may be legal. Some countries make a distinction between photographs and paintings or drawings, some do not. It is your responsibility to know your country's laws. We cannot possibly list all such details in the FAQ.
If you want to learn more, read "The Regulation of Pornography and Child Pornography on the Internet" by Yaman Akdeniz, published in February 1997 and available at: www.leeds.ac.uk/law/pgs/yaman/child.htm This is by far the most relevant and revealing essay on this matter (covers bibliography and further links).
You may also read the opinion of the District Court for the Eastern District of Pennsylvania in American Civil Liberties Union et al vs. Janet Reno, Attorney General of the United States.
And American Library Association, Inc., et al. vs. United States Department of Justice on the notorious Congressional Decency Act (CDA), to be found at:www.soci.niu.edu/~cudigest/cda/cdadec1 This is really a huge one (about 250 kB pure text).
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