It depends, because there are many different kinds of cobras. However, they all have hoods on their heads, which spread when provoked. Like all other snakes, cobras have scales and they're cold blooded. They are also very venomous.
Do you mean a Cobra? They are the only snakes with hoods to my knowledge, and sometimes go by the name "Hooded Snake". If so, there are many kinds of Cobras, such as the King, Monocle, Egyptian, Indian, Shield-Nosed, Burrowing, Desert Black, and Water Cobras.