What are the key characteristics of interfaces in programming?

Interfaces in programming have the following key characteristics:

• Define a set of methods without implementation (in Java before version 8 — only abstract methods).
• Describe a contract that classes must implement.
• Support multiple inheritance of types (a class can implement multiple interfaces).
• In Java 8+, they can contain default methods with implementation and static methods.
• Do not contain state (instance variables), only constants (static final).

Example of an interface in Java:

public interface Drawable {
    void draw(); // method without implementation

    default void print() {
        System.out.println("Drawing");
    }
}