We consider a site to be a commercial if it sells something or promotes a company that sells something.
Also sites that use PPC (pay per click) programs like Google's AdSense for example, will be considered commercial. There are always exceptions to this rule, and if you are not sure about your website fell free to ask.

If you submit a website as noncommercial or nonprofit, and we decide it is a commercial website, you will be required to pay the difference in price. In case that you decline to pay the difference your US $1.00 payment will not be refunded.
All these rules apply to our submission partners as well.

Still not sure is your website commercial or noncommercial? Contact us and we will answer your question.