Email validation ALIEN code

I would like a deeper understanding of email-validation. Specifically with the ALIEN-like string we run against user, and host in email addresses. "/^[-!#$%&\'*+\\.\/0-9=?A-Z^_`{|}-]+" for example. This string is used against the 'user' section of our email addresses.

All of the information I have found on email validation just takes pre-existing examples of this for granted, and offer to explanation for what this actually means. Can anybody here decypher this insane garble so I can have a better understanding as to what is actually taking place? I am not just a 'copy, paste, good - now the job is done." I want a deeper understanding Call me old-fashioned!

Jonathan

By user section I assume you mean foo in foo@domain.com? No matter really, I guess. I can tell you the literal equivalent for this regular expression, but w/o seeing it in context it's hard to say exactly how it's used.

" begin string
/ begin pattern (there should be a matching / at the end of the pattern)
^ match starting at the beginning of the searched string
[ begin a character class; a set of characters
-!#$%&\'*+\\.\/0-9=?A-Z^_`{|}- these characters literally, \\ is an escaped \, \/ is an escaped / (which is required so the interpreter doesn't think it's the end of the pattern), 0-9 is all numbers, A-Z is all upper case letters
] ends the character class
+ means to match one of the characters in the preceeding character class at least once, or "one or more times"
" ends string