"I got these pictures off the Internet."
This is not a sentence that should ever be uttered when one is giving a presentation, yet last week, a fellow student said those exact words.
"The Internet" is not a reference.
Chapters of books, articles in journals, and individual web pages can be references. The Internet, instead, is like a library: A place to find references. You don't cite your library in presentations.
Perhaps some of the confusion arises because all the content on the Internet is accessed through the same program (your web browser of choice). Because it is all seen in the same window on your monitor screen, it must all originate in the same place, right? Intelligent people know better, yet it is still easy to fall into the trap of assuming that images in particular and digital media in general belong not to one author, but to the vast, amorphous sea of information floating around cyberspace. If it shows up in a Google search, it's free for the taking, right?
I'm not going to lecture you on copyright laws or on how to properly cite images. But for the curious, here is a long and detailed explanation of copyright and digital images. If that's too long, pop a couple words such as "digital images" and "copyright" into Google and I'm sure you'll find a summary. I'll also recommend Chris Chesher's article on blogs and the crisis of authorship, a related but not identical topic.
The Internet. Accessed November 3, 2009.