What is the difference between an automatic transmission and a manual transmission?

Simply put, an automatic transmission sifts gears automatically, whereas a manual transmission requires you to shift the gears yourself. In an automatic transmission vehcile, you select the gear you want to be in and the transmission will shift into higher and lower gears by itself. This is better for the driver because ir does not require as much effort as the manual transmisson. Manual transmissions rely on you, the driver, to shift the gears up and down when necessary. Usually, manual transmission vehicles come with a tachometer (gague located next to the speedometer) which will allow you to see how hard the engine is working, so to speak. When the engine is pushing harder, in simple terms, you up shift by pushing down on the cluth pedal with your left foot and move the gear selecter (shifter located on the right hand side, it is a stick that comes out the floor, which is why some manuals are also called "stick shifts") to the next gear up. Then you let off of the clutch. When the engine is working less, you do the same except move the shifter handle to the lower gear. Manuals are a bit more complicated to drive and require some practice. They are usually more fuel efficent and are desired by people who tow frequently, drive up steep slopes, or race.