Internal combustion engine, ek engine hae jisme iidhan (fuel), engine ke bhittar jaraawa jaae hae, jaise ki motar ke engine. Ii external combustion engine ke opposite hae, jisme iidhan ke engine ke bahaar jaraawa jaae hae, jaise ki steam engine. Pahila internal combustion engine ke Etienne Lenoir, 1860 me banais rahaa, lekin aaj-kal ke engine ke Nicolaus Otto 1876 me banais rahaa. Ii rakam ke engine me iidhan ke jarrae ke kaara cylinder ke bhittar pressure jaada hoe jaae hae. Ii pressure ek piston, jon ek wheel se ek crank dwaara jurraa hae, ke dhakele hae. Iske kaaran wheel gola ghume lage hae aur duusr awheel jon ii wheel me connted hae, bhi ghuue lage hae. Dher rakam ke internal combustion engine rahe hae, jaise ki ek piston waala engine, inline engine, flat engine, v engine, VR engine, w engine.