The term Communities of Practice is relatively new, and yet has assumed an important place in recent discussion of informal learning. In short, it describes interactions and resultant learning when people with common interests associated with their professions interact regularly.
Communities of Practice may develop within an organization, or may involve persons who are not part of the same organization.
Communities of Practiceаexemplifyаa relatively new learning concept that is useful to training professionals, because it involves theories that help create a richer picture of learning. For example, it helps to explain and apply the concept of tacit learning, which is the ability to use and convey knowledge that, whileаuseful, those whoаhave it are at most only vaguely aware of and therefore can't formally convey it. Tacit knowledge is thought of as being conveyed informally (and unknowingly) by "rubbing off" through informal observation and imitation. Clearly, this kind of knowledge transfer is potentially extremely valuable, and something to be fostered within an organization. You can learn more about Communities of Practice through web searches and variousаother sources.