A computer message board is a type of online forum where users can post messages and communicate with each other. It is similar to an email system, but instead of sending messages directly to another user, the messages are posted on a public board for everyone to see. The messages can be viewed by anyone who visits the board, and users can respond to each other's posts. This type of communication allows for a more open dialogue between users, and it can be used to discuss topics, ask questions, and share ideas.