A Charter school is a school that is created via a legal charter. Usually (a) they are created with with an express purpose or philosophy and (b) typically they are controlled in-house and not controlled by the local school district. Laws governing them vary from state to state.
Charter schools are commonly founded as magnet schools, or as schools for at-risk kids, or those with special educational needs.
Critics of charter schools as magnets claim they syphon off the best students and leave the public schools worse off. The NEA, the largest union of teachers, supports Charter Schools, so long as they have "the same standards of accountability and access as other public schools."
Their success has been a mixed bag. Someone Charter schools do very well, and some are outright disasters.
