Abstract means: existing in thought or as an idea but not having a physical or concrete existence.
Abstract classes in oops concept means that we have a pseudo class which contains a pseudo method inside it.
An abstract class is a class that is only partially implemented by the programmer. It may contain one or more abstract methods. An abstract method is simply a function definition that serves to tell the programmer that the method must be implemented in a child class. A child classextends an abstract class.

Interface A child class implements an Interface.

  • Functions are defined outside of classes, while Methods are defined inside of and part of classes.