Imagine ordering food at a restaurant. With the traditional Future, you place your order, get a ticket number, and must periodically check if your food is ready. You can't do anything else while waiting.

With CompletableFuture, you place your order, give your phone number, and continue shopping. When the food is ready, the restaurant calls you. You can even set up a chain: "When the food arrives, put it in my car. When it's in the car, text me the parking spot."

CompletableFuture, introduced in Java 8, brings this kind of composable, non-blocking programming to Java. It's the foundation of modern async programming in the JVM ecosystem.

The Limitations of Future