What are some best practices when defining and using class constants in PHP?

When defining and using class constants in PHP, it is recommended to follow some best practices. These include using uppercase naming conventions to differentiate constants from other class members, documenting the purpose and usage of constants to enhance code readability, and accessing class constants statically using the class name followed by the scope resolution operator (::). These practices contribute to code clarity, maintainability, and consistency. To learn more, see: http://php.net/manual/en/language.oop5.constants.php