In Regrlar Expresions, there are three special characters that are used in matching patterns:
"^" - a caret is called an "anchoring operator," and matches the beginning of a string. The caret may also mean "not," which is at best confusing.
"$" - a dollar sign is another anchoring operator and matches only the end of a string.
"." - the period matches anything and is called the "match any character" operator. Many would call this a "wildcard" match character.
+ matches one or more repetitions of the preceding RE
* matches zero or more repetitions of the preceding RE
? matches zero or one repetition of the preceding RE