A contract that restricts the disclosure of confidential information or proprietary knowledge under specific circumstances. Non-disclosure agreements are often signed by companies discussing a potential partnership, or can be required by employers so that employees do not divulge confidential information about the company to non-employees. A non-disclosure agreement will usually contain very specific information, typically including exactly what type of information can not be shared, and then exceptions for when this information is allowed to be shared. A non-disclosure agreement usually lasts for a pre-determined length of time, which is generally specified within the agreement.