Short for message of the day, MotD is a frequently updated message found in online games and chat that lets all the users know about current events. When a new message is posted, the previous message is deleted or archived, so those who may have missed the message can still see past messages. Generally speaking, the message of the day can usually only be changed or updated by one or a select few individuals to prevent too many messages from being posted.
A MotD is a limited form of communication and is most often used to alert others of important events or news. For communication that requires more messages and interaction, chat, e-mail, or a forum is used.