I have seen the below pattern is used in several places (even on sof) as an example for email id validation.
the above is taken from https://www.regular-expressions.info/tutorial.html, and the quote
this pattern describes an email address.
This pattern does not take into consideration lower case alphabets (unless I am missing something).
Is there any thing further I got to understand about this patter? As this pattern can not be really used in production? Why is it so popular?