Regex Tester & Validator

This regular expression validates a URL or domain name by checking for an optional `http://` or `https://` scheme. It matches one or more optional alphanumeric subdomains followed by a primary domain name and a top-level domain (TLD). The regex ensures that domains consist solely of lowercase alphanumeric characters and dots. It is particularly useful for validating user input in web forms or parsing domain strings from text.