Reptiles, Cold Blooded?

Are Reptiles Cold Blooded? and why?

well, reptiles are called cold blooded but theyr blood is not actually cold, they just cant heat themselfs up on theyr own.
When reptiles need to warm themself up , they just lay down in the sun until they are heated enough.
When they need to cool down they just stay in the shade.
Reptiles actually need this to survive