An arbitrator is a neutral third party, appointed by the parties to a dispute in accordance with a pre-agreed process and who decides the dispute by evaluating the evidence produced by the respective parties. In deciding such disputes an arbitrator exercises several powers in accordance with the Arbitration and Conciliation act 1996 and its amendments. An award passed by an arbitrator will be binding on both the parties. 

In simple language an arbitrator basically acts as a judge between disputing parties.