An internal combustion engine works by burning fuel inside its cylinders.  
The engine takes in air and fuel through an intake valve.  
This mixture is compressed by a moving piston.  
At the right moment, a spark plug ignites the mixture.  
The rapid combustion creates high-pressure gases.  
These gases push the piston downward forcefully.  
This motion turns a crankshaft, converting linear movement into rotation.  
Exhaust gases are then expelled through a valve.  
The process repeats many times per second in every cylinder.  
This cycle is called intake, compression, power, and exhaust.  
It powers most modern cars, motorcycles, and small machines.