Regular expressions have many applications associated with searching, editing, and parsing text.
Typically, a program allows users to specify a regular expression, then it searches for text that matches that expression. In the simplest cases, a regular expression is just a literal string that must match exactly. Some characters have a special meaning when they occur in a regular expression. They aren't matched literally as in the previous example, but instead denote a more general pattern. This is accomplished by quoting the special character with a backslash.