In this chapter, we learned the concept of zero-with assertions and how it can be useful to find the exact thing in a text without interfering in the result content.

We have also learned how to leverage the four types of look around mechanisms: positive look ahead, negative look ahead, positive look behind, and negative look behind.

We also reviewed, with special interest, the limitation of the two types of look behind with the variable assertions.

With this, we conclude the travel through the basic and advanced techniques around regular expressions. Now, we are ready to focus on performance tuning in the next chapter.