Communication, the activity of conveying information through speech, writing, or other behavior.
Business communication is communication that promotes a product, service, or organization; relays information within a business; or functions as an official statement from a company.[…] Communication (from Latin “communis”, meaning to share) is the activity of conveying information through the exchange of thoughts, messages, or information, as by speech, visuals, signals, writing, or behavior. It is the meaningful exchange of information between two or a group of person.One definition of communication is “any act by which one person gives to or receives from another person information about that person’s needs, desires, perceptions, knowledge, or affective states.
Communication may be intentional or unintentional, may involve conventional or unconventional signals, may take linguistic or non-linguistic forms, and may occur through spoken or other modes.”[1]
Communication requires a sender, a message, and a recipient, although the receiver doesn’t have to be present or aware of the sender’s intent to communicate at the time of communication; thus communication can occur across vast distances in
time and space. Communication requires that the communicating parties share an area of communicative commonality. The communication process is complete once the receiver has understood the message of the sender.

Source: http://en.wikipedia.org/wiki/Business_communication