What is the notice period for leaving a company

Notice periods as per Your employer's agreements. it's different to person to person...

Normally it's 3 months...

I think it depends on the HR Policies of the company, however there is nothing like such that a company will go to court against you to breach that employment contract, however you'll not get NOC/Relieving letter from Company, and that is something because of which you will face in problem to show your experience in next job.