I am new to DnD and I am intrigued by this concept. Someone mentioned it in another post and I was curious if Wizards of the Coast has any official literature describing it?
Yes, but it does not refer to it as Theatre of the Mind
D&D 5e’s rules are built around the idea that you don’t need to use grids and minis, they are actually a variant rule in 5e. They don’t call it TotM in the book, it is simply the default style of play according to the book. Now, even though many players of D&D 5e use grids and minis (or some other tokens to represent characters), using them is still classified as a variant rule
In terms of TotM, the Player’s Handbook page 6 has this to say:
The DM tells the players where their adventurers are and what's around them, presenting the basic scope of options that present themselves (how many doors lead out of a roam, what's on a table, who's in the tavern, and so on).
Often the action of an adventure takes place in the imagination of the players and DM, relying on the DM's verbal descriptions to set the scene. Some DMs like to use music, art, ar recorded sound effects to help set the mood, and many players and DMs alike adopt different voices for the various adventurers, monsters, and other characters they play in the game. Sometimes, a DM might lay out a map and use tokens or miniature figures to represent each creature involved in a scene to help the players keep track of where everyone is.
So TotM, as described by the PHB, is simply where the DM describes the environment and the action happens in the player’s and DM’s mind. Many members of the community would agree that it stops being TotM when you start using the variant rule for grids and minis and using them as visual aids in combat.
However, if you are looking for an explicit reference to TotM, i’m not certain there is one. As far as I can tell, that term is not used in the official books.