The business of selling services to prison inmates

The United States has the highest incarceration rate in the world, with about 5 percent of the world's population, but 25 percent of the world's prisoners.

For some in the business community that represents a big money-making opportunity, and few can attest to that better than Ryan Shapiro, CEO of JPay, a company that provides various services for inmates.

"Our goal is to become the nation's digital consumer app company for prisons," Shapiro told CNBC.

How money is being made off the American prison population is the topic of both this CNBC video, and a joint report by Center for Public Integrity and CNBC.