A Link Arrow (Link Marker in the OCG) is a set of indicators unique to Link Monsters, used to denote which zones and monsters the Link Monster points to. A Link Monster's Link Rating is equal to the number of Link Arrows it has. Link Arrows are represented by red arrows radiating outward from the Link Monster's art frame.
Monsters and zones which a Link Arrow is pointing to is considered to be Linked to that Link Monster. Fusion Monsters, Synchro Monsters, Xyz Monsters, and Link Monsters can be Special Summoned from the Extra Deck to Main Monster Zones which are linked to a Link Monster.