The “ancestor” of regular expressions can be traced back to early research on how the human nervous system works. Two neurophysiologists, Warren McCulloch and Walter Pitts, have developed a mathematical way to describe these neural networks.
In 1956, an American mathematician named Stephen Kleene published a paper entitled “representation of neural network events” based on the early work of McCulloch and Pitts, introducing the concept of regular expression. Regular expression is used to describe what he calls “algebra of regular sets”, so the term “regular expression” is used.
Subsequently, it was found that this work could be applied to some early studies using Ken Thompson, the main inventor of UNIX. The first practical application of regular expressions is in UNIXqed Editor.
As they say, the rest is well-known history. Since then and until now, regular expressions have been an important part of text-based editors and search tools.