OSC stands for open sound control, its a communication protocol (imagine a modern, flexible midi). Ask wikipedia or google for more information. If you want to use it then look at the CNMAT objects [osc-route] and [opensoundcontrol] at the link below which which will get OSC data into your patch and help you route it to the right destinations. They’re really useful. Also you might want to search on the forum to see what other people have used OSC for.