A toe tag is a piece of cardboard normally attached with string to the big toe of a dead person in a morgue. It is used for identification purposes, allowing the mortician, coroner, law enforcement and others involved in the death process to correctly identify the corpse.
It usually bears the decedent's name, a case number if law enforcement is involved, and some descriptors like hair and eye color. However, in many places, actual toe tags are no longer used but have been replaced by wrist and/or ankle bands which serve the same purpose.