From CCRMA Wiki
Open Sound Control (OSC)
Open Sound Control in a protocol developed at CNMAT for controlling sound synthesis applications. It can be used simply as a replacement for midi with meaningful message names that are easy to parse out in Max/MSP or Pd. It can also be used to create a heirarchy of message that are bound for different receivers and provides support for discovering the messages an application knows how to respond to.
Open Sound Control Homepage
Open Sound Control Specification