Regular expressions "ancestors" can have been traced back to an early study on how the human nervous system works. Two neur physiologists of Warren McCulloch and Walter Pitts have studied a mathematical way to describe these neural networks.
In 1956, a mathematician called Stephen Kleene published a paper title "Neural Network Emergencies" on the early work of McCulloch and Pitts, introduced the concept of regular expression. Regular expressions are used to describe expressions he called "regular set algebra", so the term "regular expression" is used.
Subsequently, it is found that this work can be applied to some early studies using Ken Thompson's computing search algorithm, Ken Thompson is the main inventors of UNIX. The first practical application of the regular expression is the QED editor in UNIX.
As they said, the rest is a well-known history. Since then, until now the regular expression is an important part of the text-based editor and search tool.
