00 - What are Regex and why I should care?

There is a quote from James Werner Zawinski who I deeply admire and goes by like

Some people, when confronted with a problem, think “I know, I’ll use regular expressions.” Now they have two problems.

I cannot but agree with the above statement but also think regular expression (regex for short) are a powerful tool in the developer/sysadmin arsenal even if, I have to admit, every time I need to use them I go down the rabbit hole risking not to come out of it :-).