This text discusses synchronous and asynchronous processing in client-server communication. Synchronous processing is the traditional method where a client sends a request to a server and waits for a response before continuing, while asynchronous processing allows the client to continue other tasks without waiting for a response. Asynchronous processing offers benefits such as increased responsiveness, better resource management, higher failure tolerance, and parallel execution of requests. To achieve asynchronous processing, a message broker like a message queue or an event bus can be used.