Non-disclosure agreements are agreements between typically like an employee and an employer, that when the employment relationship ends there isn't the use of proprietary information by the former employee to unfairly compete with the previous employer. You can also see non-disclosure agreements in the situation where a company may be soliciting another company to provide services, and in order to be able to provide those services they have to disclose certain secret aspects, trade secrets, or proprietary information for their company to do that. And in that situation they would want a non-disclosure agreement.