What are the different validation rules available in CodeIgniter 3?

CodeIgniter 3 provides a rich set of validation rules including `required`, `email`, `string`, `integer`, `float`, `callback`, `pattern`, `min_length`, `max_length`, `matches`, `version`, `custom`, and many more. These rules can be used to validate different types of data, ensuring its integrity and correctness. You can find a comprehensive list of these rules in the CodeIgniter documentation.