The invention is a demand-based messaging system that enables a user to mark any location in a message and share the mark with a second user. The invention comprises a messaging program operable on a plurality of computers connected by one or more communications media. The program configures a first computer to accept message data, including markers and links, from a user. A marker identifies a specific location within message data, and a link refers to a specific marker within message data. The program further configures the first computer to transfer message data to a second computer. The program further configures the second computer to display the message data as it is received, and to synchronize the display with a marker when a user activates a link that refers to the marker.