L293D is an integrated circuit chip most commonly used to drive the DC motor/stepper motor/gear motor. This IC consists of two H-bridges that can drive two DC motors simultaneously and in both clockwise and anticlockwise direction. It acts as an interface between the Raspberry Pi (or any other microprocessor) and the motor.
The DC motor needs a significant amount of current to start, which the Raspberry Pi is unable to provide as an output through GPIO. For example, a 5V DC motor needs around 300 to 400 mA current, which is way beyond what is available in the Raspberry Pi's GPIO, and if we directly connect the motor to the GPIO, it can damage the Pi. So, it is recommended you avoid directly connecting of the motor to Pi.
Let's look at the pin diagram for IC L293D to get an understanding of its operation:
L293D has a 16-pin configuration. There are two Enable pins...