TDD goes hand in hand with CI, continuous delivery, or CD. Differences aside, all three techniques have similar goals. They are all trying to foster the continuous verification of production readiness of our code. In that respect, they are very similar to TDD. They each promote very short development cycles, continuous verification of the code we're producing, and the intention to continuously keep our application in a production-ready state.
The scope of this book does not permit us to go into the details of those techniques. Indeed, a whole book could be written on this subject. We'll just briefly explain the differences between the three. Practicing CI means that our code is at (almost) all times integrated with the rest of the system, and if there is a problem it will surface quickly. If such a thing happens, the priority is to fix the cause of that problem, meaning that any new development must take lower priority. You might have noticed...