class MyClass { public function foo() {} } abstract class MyAbstractClass { abstract public function bar(); } $myClassReflection = new ReflectionClass('MyClass'); $myAbstractClassReflection = new ReflectionClass('MyAbstractClass'); var_dump($myClassReflection->isAbstract()); // false var_dump($myAbstractClassReflection->isAbstract()); // trueIn this example, we have two classes – MyClass and MyAbstractClass. MyClass is not abstract, while MyAbstractClass is. We create instances of ReflectionClass for both classes, and then use the isAbstract method to determine whether each class is abstract or not. In terms of the package library, ReflectionClass is part of the core PHP language and doesn't belong to any specific package. It's available in all versions of PHP.