As the word says, it is non-disclosure of information / trade secrets and/or plan that is mutually agreed and recorded as an agreement and executed on an e stamp paper to safeguard the interest of the originator. It is generally being disclosed only to the party relevant to have that information and is part of the team that is executing the project. It stands for utmost importance and care typically at business incubation stage, as the owner / proprietorship / originator needs to make sure that plan does not get leaked / known to outside world before the actual launch of the product or service so it is always safe to have non-disclosure agreements executed on e stamp paper and signed by both the parties involved. Broadly, it is classified as short term and long term non-disclosure agreement. Short term is typical for short duration until the project is completed, so it is between the organization and the contractor. Long term is typical used by organization with their employees.