What is Public Interest Litigation (PIL) ? Who can lodge a case of public interest?

What is Public Interest Litigation (PIL) ? Who can lodge a case of public interest?

In a democracy, all political institutions are harmed for the welfare of the people. But sometimes, the actions of the government or a law passed by the government might hurt the public interest or might be against the spirit of the Constitution. In such cases, citizen have the right to go to courts to get justice; This is called Public Interest Litigation.
Anyone can lodge a case of public interest. It may be . citizen, organisation, NGO etc.