Logic Pro 9 is the latest version of Apple's music recording, editing, and mixing suite. This is not a cheap package, but you get a lot of power built in. Logic Pro 9 installs easily and the interfaces are all Apple-quality, meaning easy to use and understand.
Logic Pro 9 starts with the writing and recording component. You can see traditional musical notation on the screen if you want to compose, or you can play instruments through a MIDI interface and see the resulting notes in real time (really cool!). You can record to separate tracks, or multiple tracks at the same time. There's a huge library of effects and samples you can deploy, too. Once you've recorded the basic tracks, you lay them out in the sound editor and manipulate the different tracks to achieve the ideal sound. There's a lot of power in Logic Pro 9 for this task, including Flex Time, which lets you adjust timing easily. There's a virtual mixing console that gives you the same power as external mixing boards. You can even manipulate surround sound easily. Finally, you can add various effects and save your resulting masterpiece.
Logic Pro 9 has lots of interfaces and plug-ins for other devices and effects, and it also works with GarageBand tracks. For musicians amateur and professional, Logic Pro 9 is one of the easiest and most powerful audio suites available, and even after working with it for a year we have still not seen all it has to offer.