The text discusses various communication patterns and tools used in distributed systems. Synchronous communication involves direct remote procedure calls between two services, which can be slow if one service is offline. Asynchronous communication allows messages to be sent even if not all participants are present at the same time, using tools like queue-based or stream-based solutions. These solutions enable independent failure and parallel processing of tasks. Redis Pub/Sub is a synchronous messaging broker that focuses on fire-and-forget delivery, while RabbitMQ defaults to reliable delivery with application-level acknowledgments. Redis Streams offer a resumable Pub/Sub system, allowing clients to resume sending messages if there's a disconnection or crash. The text also touches on event sourcing, where business models are defined as an endless stream of events and other services react to it. Event sourcing can be useful for enterprise software dealing with complex domains like customers' personal data, shipping, and more. Redis Streams and Apache Kafka are compared, with both systems being equivalent in expressiveness but differing in practical details. Redis offers a simpler solution for certain use cases, such as chat applications, while Kafka is better suited for streaming architectures and reliable systems. The text concludes by highlighting the unique design of Redis and its ability to solve hard problems with few commands.