ESSB can mean two things. Extended Single Side Band or Enhanced Single Side Band.
But I would prefer Enhanced Single Side Band
Enhanced refers to doing what one can to enhance a more normal width signal of 3kHz or narrower. This is where most of ESSB play around

Basically if you spend a long time in a conversation with someone, it is to both of your benefits to sound as clean and as good as you can to make listening easier and more comfortable. With some knowledge and practice, audio processing of varying types can be applied very nicely to ham radio transmit audio.

There is one pre-requisite to all of this. You must have a rig that will actually pass the bandwidth you desire to transmit or all the processing in the world won’t change your audio. You have to have an idea of what you are trying to achieve and then the equipment you need to get there.

ESSB makes the signal sound a lot cleaner and more professional...
Do use a receiver with a wide enough bandwidth to hear the whole signal. Above all else, have fun….if any part of this hobby gets under your skin, put it away for later or move on…we only do this for fun…and to keep our hobby grow. And above all it sounds good. If some of you dont like it. Just move your dial and listen to the braodcast.

With ESSB we can achieve smooth natural sounding audio.

ESSB is an interesting pleasant mode of operation that is good for Amateur Radio. Good audio is an Amateur Radio tradition, not a crime.