Tenure is a status that appointed pedagogues achieve after completing a probationary period with satisfactory service. Once you have tenure, you cannot be dismissed without being formally charged and having a hearing before an independent arbitrator on those charges. This protects you from being fired for the personal or political objectives of a supervisor. The normal probationary period is four years, although this can be reduced by prior service or extended if the tenure grade is in doubt. To acquire tenure you must also meet all the eligibility requirements.