Symbol Description:
^ Start of a string
$ End of a string
. Wildcard - matches any character, except a newline
| Matches a specific character or group of characters on either side
\ Escape a special character

e.g. Any word characters between literal brackets

\(\w+\)

e.g. 10 digits

.{10}

e.g. Match a or b

a | b

e.g. Empty line:

^$