It didn't seem fair to write a FAQ when there are no questions that are frequently asked...
What? The Cellar Image of the Day is images; they used to be posted once per day, but now can be posted on different schedules. The images, it is hoped, will be mind-boggling, interesting, unusual or note-worthy. Typically it isn't porn, although it may sometimes contain nudity or other mature material. It may also be graphic, although the mind-boggling nature of the image shouldn't come solely from its graphic nature.
(We assume that everyone looking for porn or sexually explicit or graphic material is aware of how to get it. This is the Internet after all.)
Who? The Cellar Image of the Day is an outgrowth of The Cellar, a virtual community that has existed since 1990. It was previously posted once per day by Undertoad, who owns and operates the Cellar.
The Cellar, he points out, is not him, but rather is everyone who has ever read it, posted to it, hung out for a while, etc. Like all good communities, the comments are more important than that initial post, and all credit must go to the people in the Cellar community.
Where?The main URL is http://cellar.org/iotd.php. That always gets you to the latest image. In the left-hand navigation is a "Most recent entry". If you got here via the regular URL, but want to link to the current image, you can click on that link and get the permanent URL for that image.
In real life, the Cellar first grew up around Philadelphia and that's still its physical location... on a Penguin Computing system of course.
Why? It's really to promote the Cellar. We're looking for bright, literate people who want to hang out there. Undertoad developed the Image of the Day section on a whim and stuck with it as a sort of hobby. What you're seeing is a "repurposing" of that "content".
How? After some time managing the Cellar software, a sweet little forum package called vBulletin, Undertoad realized that he could easily create a "blog view" of the IotD section that had been developing for a year and a half. That's what the Image of the Day web site is.