Abstract: Collar stud that can be attached to an animal collar to function as a tag, collar lock, and/or electronic identification device. The stud includes a cap positionable adjacent an exterior of the collar and a base that is positionable adjacent an interior surface of the collar. A linkage interconnects the cap and base in a spaced apart fashion to allow a portion of the collar to be sandwiched between the interconnected cap and base. At least a portion of the linkage extends through an aperture of the collar portion and helps secure the stud to the collar portion. A transponder is preferably incorporated into the stud, wherein the transponder includes a memory storing retrievable information comprising an identification code. The code can be used to access a corresponding data record in a database.