What is the difference between abstract and interface i…

Abstract and interface are two distinct syntax structures in PHP, each designed to implement different concepts in object-oriented programming.

1. Abstract class
   An abstract class is a type of class that cannot be directly instantiated and can only be used as a parent class for other classes to inherit from. It can contain both regular methods and abstract methods. Abstract methods do not have specific implementation code, only method declarations, and subclasses inheriting from an abstract class must implement these abstract methods. The abstract class can also include regular methods with defined implementation code within the abstract class itself. Abstract classes are used to define a common set of properties and behaviors for a group of related classes.
2. Interface is a structure that defines the contract of a class, specifying a set of method signatures (method names, parameters, and return types), without actually implementing the specific code for these methods. The methods within an interface are all abstract, so there is no need to declare them with the abstract keyword. Interfaces can only contain method declarations and cannot include attributes or constants. A class can implement multiple interfaces using the implements keyword. Subclasses implementing an interface must implement all the methods defined within the interface. Interfaces are used to define a common interface for a group of classes, allowing for different implementation methods while ensuring all methods within the interface are implemented.

In summary, an abstract class is mainly used to define common attributes and behaviors of a group of related classes, it can contain both normal and abstract methods, and subclasses must implement the abstract methods. On the other hand, an interface is primarily used to define a common interface for a group of classes, it can only include method declarations, and classes that implement an interface must implement all methods defined in the interface.