If a person has an upatented idea, a non-disclosure agreement or confidentiality agreement is typically used. It is a form of protection for the person with the unpatented idea since with a signed NDA, a third party, to whom you show your idea, is retracted from revealing any information, except under the terms of the agreement, about your idea. An NDA also prevents a third party from marketing the idea on their own or competing with you. Without a signed NDA, a meeting about your idea would be a public disclosure.