An automatic transmissions also called auto, self-shifting transmission, n-speed automatic transmissions (where n is its number of forward gear ratios), or AT, is a type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually.

The different types of Automatic Transmissions
Traditional Automatic Transmission.
Automated-Manual Transmission.
Continuously Variable Transmission (CVT)
Dual-Clutch Transmission (DCT)
DSG (Direct Shift Gearbox)
Tiptronic Transmission.

With minimum care you’ll probably get close to 100,000 miles out of it. While that sounds like the transmission will last a long time, it only take about 7 years to put 100,000 miles on your car, that is if you drive the average of 15,000 miles a year.
While you can’t easily turn a manual transmission in a car into an automatic transmission, what you can do is to replace the clutch/transmission system into a torque converter/ automatic transmission that was available for that car. You can replace it with other automatic transmissions as well.
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