Deep work is the kind of work that takes intense focus and concentration.
It is the kind of work that is not easily replicated and instead requires years of practise and expertise to hone. This could be anything from wheel making to writing to computer programming. In this kind of work where the deeper down the rabbit hole you can go the more productive you can become.
In Cal Newport's book we learn more about deep work, what's needed to go deep and what changes in your life you should make to avoid having that ability derailed or inhibited.
The rub is that our current society really embraces the shallow - trading being productive for being busy. In the long run if you want to stay ahead of the pack you have to reject the shallow, as much as you're able to, and save your mind space for the kinds of things that help you go deep regularly and often.
Cal talks about a few strategies to do this. A few of the options are: to live a monk like life - sequestered away from society, plan your tasks across a year to get the unavoidable shallow work done up front, or simply plan your day to maximize depth.
This book is a must read for any knowledge worker or craftsman.