The engine block is the linchpin of vehicles that run on internal combustion, providing the powerhouse for the vehicle. It is called a "block" because it is usually a solid cast car part, housing the cylinders and their components inside a cooled and lubricated crankcase. This part is designed to be extremely strong and sturdy, because its failure results in failure of the car, which will not function until the engine block is replaced or repaired.
Most engine blocks are made of cast iron, although in the late 1990s, some made from plastic and other experimental materials were being used in prototype cars with the hope of developing more lightweight, efficient vehicles. A cast iron one can comprise a substantial portion of the weight of the car, and usually requires multiple people to be removed and worked on safely.
Working from the outside in, this part starts with a solid metal outside, designed to seal everything inside. A number of channels and passages inside comprise the cooling jacket and are designed to deliver water from the radiator to all the hot sections of the engine, preventing overheating. After the water is circulated in the engine, it returns to the radiator to be cooled by the fan and sent back through the engine.