The point-to-point integration of the enterprise applications requires a connector to be built for every pair of applications that needs to integrate. This creates a complex infrastructure that can be hard to manage as well as scale if new applications are introduced into the environment.
The enterprise service bus is responsible for helping different services inside an infrastructure connect to each other through the use of message-passing mechanisms. The ESB provides connectors for the applications through which the applications can connect to the ESB and send messages to the ESB.
The ESB then assumes responsibility for routing these messages to the correct service that they are intended for, thereby promoting communication between the two services inside an infrastructure.