NOC stands for No Objection Certificate. It is a type of legal certificate or document which is issued by an agency, organization, institute, to say that they have no objection to the details mentioned in the document.
Most government organizations require this certification. For example, it may be used for a lawsuit, employment, trade, immigration, and similar purposes to nullify any objection by the party concerned in the process. Furthermore, it can be used for or against in a court of law. It contains the details of the parties involved, and it is addressed to whosoever is concerned.
Let us understand it with an example:
A person who is living in Rajasthan bought a car which is registered in a different state, Punjab. In this case, the seller must get a NOC from the Punjab Regional Transportation Officer (RTO) and provide it to the buyer of the vehicle in Rajasthan. This NOC generally states that the said vehicle has no prior traffic offences against it in Punjab, and there is hypothecation against the vehicle in Punjab, or not. The buyer is required to show this document at the time of re-registering the vehicle in Rajasthan.