An online school (virtual school, e-school, or cyber-school) teaches students entirely or primarily online or through the Internet. It has been defined as "education that uses one or more technologies to deliver instruction to students who are separated from the instructor and to support regular and substantive interaction between the students. Online education exists all around the world and is used for all levels of education (K-12 High school/secondary school, college, or graduate school). This type of learning enables the individuals to earn transferable credits, take recognized examinations, and advance to the next level of education over the Internet. Virtual education is most commonly used in high school and college. 30-year-old students or older tend to study online programs at higher rates. This group represents 41% of the online education population, while 35.5% of students ages 24–29 and 24.5% of students ages 15–23 participate in virtual education. Virtual education is becoming increasingly used worldwide. There are currently more than 4,700 colleges and universities that provide online courses to their students. In 2015, more than 6 million students were taking at least one course online, this number grew by 3.9% from the previous year. 29.7% of all higher education students are taking at least one distance course. The total number of students studying on a campus exclusively dropped by 931,317 people between the years 2012 and 2015. Experts say that because the number of students studying at the college level is growing, there will also be an increase in the number of students enrolled in distance learning. Instructional models vary, ranging from distance learning types which provide study materials for independent self-paced study, to live, interactive classes where students communicate with a teacher in a class group lesson. Class sizes range widely from a small group of 6 pupils or students to hundreds in a virtual school. The courses that are independent and self-paced are called asynchronous courses. Typically for this type of learning, the students are given the assignments and information and are expected to complete the assignments by the due date. This is done on their own time. There is no scheduled time when the class meets. Usually, the only interactions that take place are through discussion boards, blogs, and wikis. On the other hand, synchronous online courses happen in real-time. The instructor and students all interact online at the same time. This is done either through text, video,