MSP is a graphical programming
environment designed for music and multimedia
applications. MSP is a new addition to an older program, Max
operates on incoming and outgoing MIDI
signals (and generates MIDI
signals), while MSP operates on and/or generates digital audio
Max and MSP are not seperate programs, however, they are merged into one program and elements from each can be used simultaneously (i.e. using a MIDI signal to control a digital audio signal, and vice versa).
Max is named for Max V. Mathews, computer music pioneer and sailing enthusiast. MSP does not officially stand for anything, but could perhaps stand for "Max Signal Processing" or "Miller S. Puckette" (the original creator of MAX), as well as other, less probable, acronyms.
For a brief description on the way Max (and therefore MSP) works, see the node on Max.
MAX/MSP are now owned by Cycling '74 (www.cycling74.com)