What is Class B push-pull amplifier?

When we get amplifier output current for 180 degrees of input. then it's called B class amplifier.

In a push pull class B amplifier one of the two power transistors or other amplifying elements handles the positive half of the waveform and the other element handles the negative half of the waveform.

In practice, push pull audio amplifiers are usually class AB; each power transistor handles slightly more than 180 degrees of input. This minimizes distortion (crossover distortion) when one of the two transistors ceases output and the other takes over.