The informal transmission of information or filtered information is called

The informal, unofficial passing of information or filtered information through social relations within an organization is the grapevine.

It springs up spontaneously from the personal and social ties among employees and runs alongside the official channels.

Gossip is loose talk about people rather than the network itself that carries filtered organizational information.

Vertical communication moves formally up or down the chain of command between superiors and subordinates.

Horizontal communication is the formal exchange between people at the same level.

The grapevine is fast and pervasive but prone to distortion and rumour.