Regular Expressions
Regular Expressions are way of matching patterns of string in another string. This standard notation helps extremely well to find patterns of string within another string rather than traditional way of searching the pattern in all permutations and combinations. Regular Expressions are supported by most of the programming and scripting languages. For history and theory behind regular expressions look at this link in wikipedia but if you want to know the patterns and the explanation for example how to use in JavaScript here is the reference to it - “Regular Expression Patterns“, though this is applicable in most of the languages.
