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 and a day, 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.