A virtual school or cyberschool describes an institution that teaches courses entirely or primarily through online methods. Though there are tens of thousands of commercial and non-accredited courses available online, the term "virtual school" is generally reserved for accredited schools that teach a full-time (or nearly full-time) course of instruction designed to lead to a degree. Virtual public and private schools serving every grade level including graduate programs may elect to pursue accreditation through various regional and national organizations. Accredited schools must meet rigorous standards as defined by the issuing organization and are designed to ensure that students are receiving the highest quality instruction and education. All or a majority of the student services are conducted via Internet technology. The virtual school differ/contrasts from the traditional school through the physical media that links administrators, teachers, and students. Virtual schools are an alliance of public distance learning schools. Many states in the United States have their own virtual school often with a student population numbering in the thousands.