<p>A computer network-based messaging system includes a multiple-layer chat filtering system for controlling the content of messages sent by users. A computer receives a message including a plurality of words entered by a sender. A word database includes a plurality of permitted words which are allowed to be transmitted. A phrase database includes a plurality of prohibited phrases which are not allowed to be transmitted. At least one of the plurality of prohibited phrases consists of a plurality of individual words that are each included in the word database. A message sending part that transmits the message over a computer network only if all of the plurality of words entered by the sender are contained in the word database and none of the plurality of prohibited phrases are contained in the message.</p>
