PIL an overview

INTRODUCTION
“Public interest litigation has become the people’s tool fashioned by judges to enforce the obligations of the state, its institutions, and its functionaries to explore and discover ways and means of giving life and soul to the preambular assurances via the judicial process.”
-Justice O.Chinnappa Reddy
"Public interest Litigation", in simple words, means, litigation filed in a court of law, for the protection of "Public Interest", such as pollution, Terrorism, Road safety, constructional hazards etc.
PUBLIC INTEREST LITIGATION is not defined in any statute or in any act. It has been interpreted by judges to consider the intent of public at large. Although, the main and only focus of such litigation is only "Public Interest" there are various areas where a PUBLIC INTEREST LITIGATION can be filed.
Public Interest Litigation, in Indian law, means litigation for the protection of public interest. It is litigation introduced in a court of law, not by the aggrieved party but by the court itself or by any other private party. It is not necessary, for the exercise of the court's jurisdiction, that the person who is the victim of the violation of his or her right should personally approach the court. Public Interest Litigation is the power given to the public by courts through judicial activism.
Such cases may occur when the victim does not have the necessary resources to commence litigation or his freedom to move court has been suppressed or encroached upon. The court can itself take cognizance of the matter and precede suo motu or cases can commence on the petition of any public-spirited individual.1

DEFINATION OF PUBLIC INTEREST LITIGATION
IN BLACK'S LAW DICTIONARY : "Public Interest Litigation means a legal action initiated in a court of law for the enforcement of public interest or general interest in which the public or class of the community have pecuniary interest