1+/1+ counter rules

120 - Counters
120.1 - A counter is a marker placed on an object or player that modifies its characteristics and/or interacts with a rule, ability, or effect. Counters are not objects and have no characteristics. Notably, a counter is not a token, and a token is not a counter. Counters with the same name or description are interchangeable. [CompRules 2009/07/08]
120.1a - A +X/+Y counter on a permanent, where X and Y are numbers, adds X to that permanent's power and Y to that permanent's toughness. Similarly, -X/-Y counters subtract from power and toughness. See Rule 612.3. [CompRules 2009/07/08]
120.1b - The number of loyalty counters on a planeswalker on the battlefield indicates how much loyalty it has. A planeswalker with 0 loyalty is put into its owner's graveyard as a state-based action. See Rule 704. [CompRules 2009/07/08]
120.1c - If a player has ten or more poison counters, he or she loses the game as a state-based action. See Rule 704. [CompRules 2009/07/08]
120.2 - If a permanent has both a +1/+1 counter and a -1/-1 counter on it, N +1/+1 and N -1/-1 counters are removed from it as a state-based action, where N is the smaller of the number of +1/+1 and -1/-1 counters on it. See Rule 704. [CompRules 2009/07/08]
120.3 - If an effect says to "move" a counter, it means to take that counter from the object it's currently on and put it onto a second object. If the first and second objects are the same object, nothing happens. If the first object has no counters, nothing happens; the second object doesn't get a counter put on it. If the second object (or any possible second objects) are no longer in the correct zone when the effect would move the counter, nothing happens; a counter isn't removed from the first object. [CompRules 2009/07/08]
120.4 - If a spell or ability refers to a counter being "placed" on a permanent, it means putting a counter on that permanent while it's on the battlefield, or that permanent entering the battlefield with a counter on it. [CompRules 2009/07/08]