To message is to intentionally send a specific signal to an agent.
A message is a specific signal which is intentionally shared in one or more specific channels.
Data is often transmitted in intentionally separated messages instead of by streams in open channels. Such intentionally separated messages are a basic type of media item.
For example, agents often use the ENTER key or a Send button to intentionally transmit all data elements within a specific data entry field to other agents. Agents interact this way through "instant messaging" applications, email, and the vast majority of website interfaces.
Digital messages may contain any type(s) of digital data, including inline (contained and labeled) media items and hyperlinks.