From iPhone Development Wiki

launchd is a "system wide and per-user daemon/agent manager." It is a daemon that handles daemons. Use launchctl to interface it.

Configuration files

launchd uses plist files to know how to interact with each installed daemon/agent. It is explained here.

Configuration file locations

Location Type
/Library/LaunchAgents Administrator controlled Agents for a specific user
/Library/LaunchDaemons System-wide daemons provided by the administrator.
/System/Library/LaunchDaemons Default daemons provided by iOS.

External links