CakePHP is a PHP web development framework that follows the MVC pattern. It uses conventions over configuration, so table names, primary keys, and other structures follow standard naming conventions to reduce configuration. CakePHP 3 introduced entities/objects returned instead of arrays, separated and reusable validation, associations no longer defined as properties, and patching entities to remove unneeded data. It also defaults to not retrieving associated data to avoid bloated queries. CakePHP 3 supports PHP 5.4.16+ and requires the mbstring and intl extensions. While migration tools exist, a full migration from CakePHP 2 to 3 is not recommended due to changes, and a redesign adopting CakePHP 3 standards is suggested instead.