By definition, a charter school is an independently managed public school that operates under a charter, or contract, approved by local governing agencies. Charter schools can be started by parents, teachers, community leaders, educational entrepreneurs, school districts and municipalities. Each school's charter details every aspect of its operation, including how student performance is measured. Charter schools must have free and open enrollment and be part of state testing and federal accountability programs.
School charters are reviewed periodically and can be renewed or revoked if, for example, the schools don't deliver expected student results. In fact, though charter schools now number more than 7,000, earlier in this decade nearly 2,500 were closed.
In all, 44 states and the District of Columbia have charter schools. And the laws and rules governing them vary widely, making it hard to evaluate the concept.
Some studies have shown that charter students outperform students at traditional public schools in elementary reading and middle school math. They're equal to or underperforming in math and reading at the high school level.
It's hard to know why some charters succeed and others don't, but it could be that successful ones use proven strategies like smaller class sizes and more school time and parent involvement, features you might look for when evaluating one in your area.