The boot sequence in Mac OS X offers a number of advanced features that are not yet common in other UNIX-based and UNIX-like operating systems. These differences are significant enough to warrant their own document: System Startup Programming Topics.
In that document, you will learn about legacy startup items (the recommended way to start daemons prior to v10.4), launchd (the recommended way in v10.4 and later), and why you should start your daemons with these mechanisms instead of modifying rc files.
Last updated: 2008-04-08