Since we have teachers and students from over 100 countries, it's confusing to talk in individual currencies when talking to everybody. Therefore, we use a common currency "TeacherOn coins" or just "coins" for all kinds of transactions. 1 coin is approx $0.015. You can view the price for your local currency on Buy coins page when logged in.
Teachers use coins to contact students and apply to potential teaching opportunities. Please see details at How it works for teachers
Students use coins to contact teachers. Please see details on How it works for students.
They don't. Unlike other websites, our coins don't expire.