Abstract Classes in PHP
An abstract class is one that cannot be instantiated, only inherited. You declare an abstract class with the keyword abstract, like this −
When inheriting from an abstract class, all methods marked abstract in the parent\’s class declaration must be defined by the child; additionally, these methods must be defined with the same visibility.
abstract class MyAbstractClass { abstract function myAbstractFunction() { } }
Note that function definitions inside an abstract class must also be preceded by the keyword abstract. It is not legal to have abstract function definitions inside a non-abstract class.