Creative Commons Noncommercial often shortened to NC is clause in the Creative Commons license that restricts sharing and use to Noncommercial use.
Content licensed with this clause is not usable on Appropedia. See Non-commercial licenses vs open licenses for discussion why.
For details on why the Appropedia Foundation chose the CC-BY-SA license, which allows commercial use, and the problems with Non-Commercial licenses, see Non-commercial licenses vs open licenses.