How do I record what's playing on the Mac?

I want to record a song playing on the Mac, but I don’t want to use the internal microphone. On Windows I can do it easily. There seems to be only “Core Audio” for a Host and “Internal Mic” as an input. How do I get more choices? This is to record on to Audacity from YouTube, for example.

You could buy the music in iTunes.

Macs don’t have any natural ability to record streaming audio, so you’re stuck with third party utilities.

Post back how it goes. I use SoundFLower which is no longer supported.