How to validate email in Oracle APEX with Regular Expression or Regex 

^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^.-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$
^: Start of the string.
[a-zA-Z0-9_!#$%&'*+/=?`{|}~^.-]+: One or more characters that can be letters (a-z, A-Z), digits (0-9), underscores (_), and some special characters like !#$%&'*+/=?`{|}~^.- for the username part.
@: Match the "@" symbol.
[a-zA-Z0-9.-]+: Match one or more letters (a-z, A-Z), digits (0-9), dots(.), or hyphens(-) for the domain name.
\.: Match a period (dot), which separates the domain name and top-level domain (TLD).
[a-zA-Z]{2,4}: Match the TLD, consisting of 2 to 4 alphabetical characters.
$: End of the string.

Наука