In PHP an extended class is always dependent on a single base class, that is, multiple inheritance is not supported. Classes are extended using the keyword 'extends'.
PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language. Originally created by Rasmus Lerdorf in 1994, the PHP reference implementation is now produced by The PHP Group.
Generally, inheritance has three types, single, multiple and multi level inheritance. But, PHP supports only single inheritance, where, only one class can be derived from single parent class.