Certain companies ask an employee to sign an NDA (non-disclosure agreement) in order to protect their trade secrets. The reason being it allows their company to operate at a higher level and less risk. Things you should consider before signing an NDA is to make sure the definitions of proprietary and confidential information are thoroughly defined in it. More importantly, understand the documents properly and the consequences of breaching this information. When you find things suspicious in the NDA, then raise a question and clear your doubts before signing it. Also, sometimes it is possible to negotiate, ask for clarifications and information on terms of the agreement.