What are Java interfaces?

Java is a high-level, object-oriented programming language known for its platform independence. This is achieved through the Java Virtual Machine (JVM), which allows Java applications to run on any device that has the JVM installed. This 'write once, run anywhere' capability is one of Java's key features. 
 
Explain Java's platform independence.

Java is known for its portability, object-oriented nature, strong memory management, and robust security features. It uses bytecode for portability, has automatic garbage collection, and provides a secure environment through its built-in security features. These characteristics make Java suitable for various applications. 
 
List features like portability and security.

The Java Virtual Machine (JVM) is an abstract computing machine that enables Java bytecode to be executed. It provides an environment where Java programs can run, converting bytecode into machine code for the host machine. This allows Java to be platform-independent and portable across different systems. 
 
What does JVM do?

A Java class is a blueprint for creating objects. It encapsulates data and methods that operate on that data. For example, a class 'Dog' might have attributes like 'breed' and 'age' and methods like 'bark()' or 'fetch()'. Classes facilitate the principles of Object-Oriented Programming (OOP). 
 
Define a simple class.

Java interfaces are abstract types that define a contract for classes without providing implementation. Unlike classes, interfaces cannot hold state and only declare methods. A class can implement multiple interfaces, allowing for more flexible designs. For instance, an 'Animal' interface may include methods like 'eat()' and 'sleep()'. 
 
How do interfaces differ from classes?