that is, the Processing programming language.
I saw a tag "processing" and used that, but none of the other questions with the same tag seem to be about the unfortunately named language called "Processing".
update: I'm in a Processing class at work now, and I've just learned that it was originally called Proce55ing. Aside from the name, it's otherwise a really neat visualization environment. Check it out at http://processing.org!
update 2: It turns out Processing is a Java thing and not its own language, although the project's web site does suggest that. Therefore, Konrad's suggestion seems most logical, and removing all the random "processing" tags will be a good thing overall.
Processing is an open source programming language and environment for people who want to program images, animation, and interactions.