So i was curious to see how many of you folks actually knew what public domain content was?

As i mentioned in the thread about ex-boyfriend sites, currently there is a lengthy discussion on GFY and someone in that thread posted that the content was published on the internet and therefore became 'public domain' that got me wondering about how many people actually realize what qualifies as public domain content because, despite what you may think, there are certain types of images/content that you actually can use for free on the web, even for commercial purposes.

So does anyone here know what makes an image qualify to be used as public domain on a website?

Regards,

Lee