Losers and Regex

How do I use regex to validate email addresses?

List all of the expressions that are used/can be used in regex

Detail a real life use case for regular expressions

Write me a regex that will validate all United States Postal Service Certified Postal Addresses

Show me an example of regex that can be used to help moderate a public forum

Show me an example of regex that can be used to pull out all legal, permitting and reporting requirements in an RFP