What is the veil in Harry Potter 5?

In Harry Potter and the Order of the Phoenix, the veil is a mysterious object located in the Department of Mysteries within the Ministry of Magic. It resembles a long, thin piece of fabric that hangs in the middle of a grand hall and cannot be seen by most individuals. Only those who have suffered mental or emotional trauma can perceive the veil, which seems to hold some allure to them, as it supposedly serves as a conduit between the world of the living and the realm of the dead.