Historically, education in the United States has been split between private schools, and traditional public schools. However, this dynamic changed in 1991 when Minnesota passed the first law establishing charter schools in the state. Since then, a majority of states have some kind of charter school system. But what exactly is a charter school?

Charter schools offer education ranging in grades K-12 without charge to students. Charter schools are funded with tax dollars, but are generally subject to fewer rules and regulations than traditional public schools, and they usually receive less public funds per pupil than public schools. Charter school students typically take the same state-required standardized tests as public school students.

Depending on state law, these schools can be started by parents, teachers, non-profit groups, corporations, or even government organizations. Charter schools may focus on specific skills and subjects like math or science, or may be aimed at students who require alternative learning methods—such as teaching lessons that use visual or more hands-on approaches. But these entities just can’t start one whenever they please. They must first obtain authorization from either the school district, city, or state—depending on how the charter school laws are structured.

And the charter school model has achieved various levels of success. Over the past 25 years, the number of charter schools in the U.S. has skyrocketed, forcing more competition and faster improvement among existing public and private schools. As of 2016, there are almost 7,000 charter schools serving 3 million students. And since 2000, charter school enrollment has increased by 600 percent.

But as charter schools have become more popular, opposition has grown. Teachers unions and other public school activists argue that charter schools take money away from traditional public schools. However, it’s unfair to hold minority parents and students hostage in underperforming public schools. Overall, charter schools have provided an entrepreneurial challenge to the status quo and delivered results that make it worth expanding this option for parents.

According to a 2015 Stanford study, not only do charter schools provide significantly higher levels of growth in math and reading for all students, but minority and low income students benefit disproportionally more.

Charter schools are becoming a bigger part of the U.S. education system every year—and for millions of American families they offer a much-needed choice that’s different than a one-size fits all public school.

Every other sector of the American economy has benefited from the ability to compete and improve—why not Education?