Normally used as in what you are and aren't allowed to do with your InterNet connection by your ISP, place of education or place of work.
Standard examples for residential service include:
- no running servers from your home machine/network
- no deliberate hacking/viruses/port-scanning to originate from your machine
See HoihoAcceptableUsePolicy for the WlugServer AUP, and http://www.wlug.org.nz/archive/mailing-list-aup.txt.