Shaders are items used by Guardians to customize item colors.
In Destiny, Shaders can be used alter the color and texture of the player's currently-equipped armor set after reaching level 20. They have unlimited uses, but only one Shader can be equipped at a time. Shaders are obtained from vendors in the Tower, the Reef, and the Iron Temple, or as activity rewards.
In Destiny 2, Shaders alter individual pieces of armor, weapons, and other equipments. Shaders can be acquired from the Eververse Store, vendors or upon the completion of activities and challenges. [1]