Answer:
grapevine
Step-by-step explanation:
Grapevine is an informal way of communication, it is more friendly manner, there is no organized manner or format in this case.
Many times this form of communication is more easy to make and access, but that the communication is not feasible for serious discussions.
Every aspect has its pros and cons, this type of communication is not preferable for serious discussions, and where the information is not complete, it turns it into rumors, and non trust able information.
This further leads to the harm to people for whom the information is vital.