To translate this to simple-speak: regular expressions are a series of patterns that can be used to perform powerful matching operations when simple wildcards and find/replace utilities stop being useful.
Some interesting scenarios where regex is commonly deployed include:
Making sure passwords are strong enough Identifying whether an email address is valid Validating credit card number inputs from different providers (Visa, Amex etc) Checking for valid address inputs Making sure IP addresses are in the right format Validating URLs Checking for valid bitcoin addresses And for some more regular use cases in SQL:
Identifying specific patterns in a long string to identify customers Searching for multiple date formats in a free-text field Find and replacing multiple substrings without nested SUBSTRING functions Identifying matched patterns and re-inserting them to create a new text field (this is super useful!)