What is a driver amplifier

What is a driver amplifier? Why and in which cases it is used?

Regards

The driver i know is the intermediate amplifier(not a final state),that drives other state .
For the input that final amp can't handle ,it is used.
It drive other active devices rather than passive.

In my opinion, a driver amplifier can be simply considered as a driver (to amplify power) that is capable of providing sufficient current (power) to drive the following stage of the circuit.

Hello

As an exemple for a OPAM (To my mind) this term correspond
either to the
- differentiel entry
- either to the preamplifier just before
the power amplifier double stage.
I think that it looks more like the power stage
usually makes by two HIGH MOSFET input impedance
like a darligton

Lets Consider this Problem :
First You have a little dc motor and you want to turn it on with CMOS IC or
Microcontrollers .
First Most Little dc Motors consume Currents more than 0.1 Amper.
But Your Chip can't source this Current.

So ,Before you connect your motor to the IC you must amplify it's Current By
Buffer (Driver) which can Source more amper than the Chip.

Buffer Has two Benefits:
1- it Source or Sinks more Current to drive a motor
2- It Unilaterize and isolate the Commander Circuit to Motor.
This is Very Good Because any fault in Motor (Short Circuit )
Damage the Buffer first And it Acts Like Fuse (Because Of isolating Between
Commander and Buffer)

They Are Many Types Of Drivers or Buffers Like:
1- Power OpAmps in Unity Gain Configuration.
2- Power Mosfets & Darlington (LIKE ULN2803 Darlington IC)
3- Some Buffers that they can't Produce High Power But Very Suitable
for Isolating Digital Circuits Like (74LS244 Tristate Digital Buffer)