Regular Expressions cheatsheet -

Match zero, one or more of the previous
Lau* matches "Lauuuu" or "La"

Match one or more of the previous
Lau+ matches "Lau" or "Lauu" but not "La"

Match zero or one of the previous
Lau? matches "Lax" or "Lau" or "La"

Used to escape a special character
Hello\? matches "Hello?"

Wildcard character, matches any character
do.* matches "doc", "dot" etc

Matches a range of characters

Group characters

Logical OR

Matches a specified number of occurrences of the previous

Beginning of a string.
or negation in []

End of a string

any letter

any uppercase letter

any lowercase letter

any digit

any alphanumeric

any hex digit