Each time there is a chance to play spells or abilities in the game, the active player gets Priority. The active player is the player whose turn it is, and Priority is the right to play a spell, ability, or special action.

If you have Priority, you can play a spell or ability and add it to the Stack. If you do play one, you keep Priority afterward and get the chance to play another. And another. And another. Until you decline to play one, which is called passing.

Once you pass, your opponent gets Priority (or the next player in turn order if you play multiplayer games). They get the chance to play, and so on.

Once all players pass in succession (meaning that no one wants to play anything), you resolve the spell or ability on top of the Stack. Then the active player gets Priority again. This is an advantage that the current player gets over other players. They get Priority first all the time.

If the Stack happens to be empty, then you end the current step of the turn in which spells and abilities were being played.

Right before a player gets Priority, you apply any State-Based Effects and handle any Triggered Abilities. These will be described in more detail in future articles.

Also, you have to have Priority and have an empty Stack during your main phase in order to play a Land. This doesn't go on the stack, though. It's a special action that puts the land into play. You keep Priority after doing this.

That's about all there is to Priority as far as rules go. It's pretty simple. Let's take the simple example from Crystal Clear - 1C and go through it with an eye for Priority.

A	B	C	D
(It's Bob's turn, so he's the active player and he has Priority)
A1) Bob plays Twiddle : He pays {U} and chooses Carl's Prodigal Sorcerer as the target.
	(Bob wants his spell to resolve, so he passes. Carl gets Priority.)
	B1) Carl plays Prodigal Sorcerer 's ability: He taps the Sorcerer and chooses Bob as the target. It goes on the stack (shown indented here to mean that it is on top of the Twiddle.)
		(Carl wants his spell to resolve, so he passes. Bob gets Priority.)
		(Bob doesn't have anything he wants to do so he passes. Since both players passed, the top spell on the stack resolves.)
	Resolve B1) Resolve the Sorcerer ability: The Sorcerer deals 1 damage to Bob.
	(Bob gets priority again since a spell resolved and he's the active player. He doesn't want to do anything, so he passes. Carl gets Priority.)
	(Carl doesn't want to do anything, so he passes. Since both players passed, the top spell on the stack resolves.)
Resolve A1) Resolve the Twiddle: Bob chooses whether to tap or untap, and chooses tap. Since the Sorcerer is already tapped, this does nothing.
(Bob gets priority again since a spell resolved and he's the active player.)

The active player gains Priority at the beginning of most steps and at other opportunities to use spells and abilities. He or she also gains priority just after any spell or ability on the stack resolves. [408.1c]

The player with Priority can play a spell, ability, or special action. After doing so, they keep Priority and get the chance to play again. Priority moves to the other player (or next player in turn order for multiplayer) once that player passes. [408.1c]

Whenever all players have passed in succession, the top spell on the stack resolves. If the stack is empty when all players have passed, the current step of the turn ends. [408.1c]

The legal special actions are playing a Land (which you can only do on your turn, during the main phase, and when the stack is empty), turning a face-down permanent face up, and ending an effect that has an optional ending. You play a special action when you have Priority. You keep Priority afterwards. [408.1i]

Each time a player would get Priority, the game applies any State-Based Effects, then any Triggered Abilities are handled. This is repeated until no further actions of these types are required. Then the player actually gets Priority. These topics will be handled in future articles. [408.1b]

Q: The people I play with don't use Priority. Is that a problem?

No. In most games, people will not explicitly say that they are passing priority and go through all the back-and-forth because it slows down the game. And most of the time this is okay, since Priority rarely matters in casual play.

So we recommend that you keep playing the way that keeps the game smoothly moving along, except when you know that timing might matter. Then slow down a bit and fall back on being formal for a while. Be sure to let your opponent know that you want to be more formal before it matters.

How will you know if it matters? You won't always, but sometimes you know you're going to play a card that is more complex and you can slow the game down to avoid confusion.

Switching in and out of formal timing can be considered frustrating to players... but so can staying in it.