The informal grapevine network model is an informal communication channel that spreads throughout an organization irrespective of authority levels. It exists more at lower levels and is very active in most organizations. There are four types of grapevine: single strand, gossip, probability, and cluster. The grapevine generally develops due to reasons like uncertainty during recessions, preferential treatment of some employees, and a lack of formal channels to exchange views. While it can spread information quickly and provide feedback, the grapevine also carries risks like spreading partial or false information that can reduce productivity and harm an organization's goodwill.