If you mean where does pornography come from historically, pornography first began after the enlightenment and the printing press in Europe. Digital pornography may have started in the late 1950s, when an anonymous IBM employee displayed a lady from the Esquire magazine onto the screen of a 238 million$ computer screen. So, pornography using some technology tends to come into existence soon after the technology is invented.

If you mean where does each pornographic item come from, it usually comes from artists or individuals, whether that would be a person taking pictures of themselves, someone drawing a picture, or someone writing a story.
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