Regular Expression is a pattern or sequence of characters. This method is effectively used to match the specific pattern within a string and to extract the pattern of the string precisely to do various manipulations which may include splitting strings, replacing characters. Regex is one of the most powerful ways to do string manipulation. It is preferred for string functions for specific string manipulation needs.
The regex tutorial is aimed at the basics of the Regular expression i.e. to do string manipulation using the basic meta characters available in almost all languages in common.