A feature in Apples new OSX which allows a developer to transparently use java objects in objective-c and vice versa. In the background the bridge creates a proxy object for the translated object resulting in some overhead. The big advantage is that a developer can use both languages in a single project. This doesn't make sense untill you think about libraries, there are a lot of excellent java libs out there but very few for objective-c. The objective-c developer now has a whole new world of code to integrate and use