Regular expression characters
Each character or special character in a regular expression represents one character. Though some special characters, such as, the range of lowercase characters represented by [a-z], may have multiple matches, only one at a time is matched. Thus, [a-z] will only find one of these 26 characters at one position in a string being searched. Just as strings have special characters, namely, escape sequences, regular expression patterns have various kinds of special characters and metacharacters that are explained below.
Regular expression attributes