An Exotic Shard is a material in Destiny. They are used for the final upgrade on and to ascend Year 1 exotic weapons and armor. For Year 2 gear, they are a required material for infusing exotic weapons and armor.
Exotic Shards can be obtained by dismantling exotic gear. An exotic item that has the max amount of experience can be dismantled for 2 Exotic Shards. This only requires the experience to be maxed; the nodes do not need to be purchased. An exotic without the max amount of experience will only provide 1 Exotic Shard when dismantled.