Cocoa is a visual programming language developed at Apple's R&D department in the early through mid 1990s. It lets users (even kids) program by giving objects example rules that those objects then follow when run. Thus, users are able to program without having to gain an abstract understanding of what they are trying to make their objects do.
This is a category for sites and Web pages on the Cocoa visual prgramming lanaguge. This is NOT the place to submit links about the Cocoa libraries found in Mac OS X. Those are likely found in Computers/Systems/Apple/Macintosh/Development/Mac_OS_X.