Charter schools are an attempt to revitalize the public school system by allowing new "schools" (just corporations, really) to operate under special "charters". These schools receive government money for each student who attends, and are subjected to a relatively simple set of state and federal standards. Otherwise they can pretty much do what they like.

This can sound good on paper. Unfortunately, rebuilding public education will not happen without simultaneously rebuilding public education funding. Charter schools do not do this. Instead, they divert and divide funding, leaving themselves, as well as the public schools they are meant to "compete" with, with less overall.

Education, similar to health care and the military, are not fundamentally profitable enterprises. You cannot make money selling a decent education. It's too costly per student for that student's family to pay on their own. However, as a society, it makes sense for us all to pitch in and help, because a better educated society is good for everyone, and a poorly educated society is bad for everyone. Attempting to "privatize" American education is merely an invitation for rather harrowing "profit taking" schemes by the (opportunistic) charter school corporations.