More precisely, in communications science, a message is information which is sent from a source to a receiver. Some common definitions include:
Any thought or idea expressed in a language, prepared in a form suitable for transmission by any means of communication.
An arbitrary amount of information whose beginning and end are defined or implied.
In communication between humans, messages can be verbal or nonverbal:
A verbal message is an exchange of information using words. Examples include face-to-face communication, telephone calls, voicemails, etc.
A nonverbal message is communicated through actions or behaviors rather than words.
Examples include the use of body language and the actions made by an individual idea.