Using Regular Expressions Metacharacters – understand escaping

Regular Expressions Metacharacters are characters that have special meaning within regular expressions. The period (.) is a metacharacter; it is used to match any single character. The star (*) is a metacharacter; it is used to match repetition of a single character any number of times. Similarly, the left bracket ([) is a metacharacter; it is used to mark the beginning of a set and the right bracket (]) is a metacharacter; it is used to mark the ending of a set.

In regular expression metacharacter has special meaning, so these characters cannot be used to refer to themselves. For example, you cannot use a . (period) to match .(period) or * (star) to match * (star).

\(backslash) is a metacharacter which helps us to escape the meaning of the special characters and treat them as a normal character. Thus, "\$", "\^", "\.", and "\\", match the literal characters "$", "^", ".", and "\", respectively.