One of the commonest forms of social control. Rumor is a method of praising or damning another's actions, and expressing the community opinion. Commonly denigrated in just about every society, rumor (or rumour, as i more frequently spell it), is an avenue for subaltern expression of social power. This is, it is a regulatory technique that can be used by the most disempowered (generally, stereotypically, women) in a community.
Rumor is just about invariably a conservative force, but may occasionally act in opposition to entrenched and publically sanctioned top-down expressions of power (tribal leadership, church, law).