Historical Rules · 29 September 2017
Rule 701.12a
Official source text from the 29 September 2017 Rules release
To play a land means to put it onto the battlefield from the zone it’s in (usually the hand). A player may play a land if he or she has priority, it’s the main phase of his or her turn, the stack is empty, and he or she hasn’t played a land this turn. Playing a land is a special action (see rule 115), so it doesn’t use the stack; it simply happens. Putting a land onto the battlefield as the result of a spell or ability isn’t the same as playing a land. See rule 305, “Lands.”