What does the term commodity Internet refer to?
A general, commercially-available connection to the "regular" Internet, as opposed to a special-purpose restricted network like Internet2 or the US military's NIPRNet, or some other specialized backbone network. Generally, a commodity Internet connection offers no content, application protocol, or destination restrictions or quality-of-service controls.
The term "commodity" is used because you could basically get the exact same thing from many competing providers. They may vary in details like where and how you're connected, but in theory if you paid enough you could get the same thing from anyone.