What do you mean by 'grapevine?

What do you mean by 'grapevine? Explain two types of grapevine netwoty along with diagrams.
Explain different networks of grapevine communication.

The network of informal communication is called ‘grapevine’. This is because it spreads throughout organisation with its branches going out in all directions.
Grapevine Networks
Some popular grapevine networks are as follows:
(i) Single strand network In this network, each person communicate with another in a sequence.

(ii) Gossip network In this network, one person communicates with all on non-selective basis.

(iii) Probability network In this network, any person can communicate with anyone else randomly.

(iv) Cluster network In this network, an individual communicates with only those people whom he trusts.