What is a Route in Apache Camel and how do you define one using the Java DSL?

A Route is the fundamental unit of integration logic — a complete message flow: where messages originate (from()), what processing they undergo (EIPs, Processors, Beans), and where they are sent (to()). Each route runs as an independent pipeline inside the CamelContext, identified by a unique route ID.

public class OrderRoutes extends RouteBuilder {
    @Override
    public void configure() {
        from("file:/orders/input?noop=true")
            .routeId("file-to-jms")
            .log("Processing: ${header.CamelFileName}")
            .unmarshal().csv()
            .split(body()).to("jms:queue:order-items").end();
        from("jetty:http://0.0.0.0:8080/api/orders")
            .routeId("http-router")
            .choice()
                .when(header("type").isEqualTo("express"))
                    .to("jms:queue:express-orders")
                .otherwise().to("jms:queue:standard-orders")
            .end();
    }
}

Key rules: exactly one from(uri) per route; to(uri) sends to a producer without ending the route; routeId() assigns a stable ID for monitoring and testing. In Spring Boot, annotate a RouteBuilder subclass with @Component for automatic registration by camel-spring-boot.