When your services need to talk without waiting on each other, Apache RocketMQ carries the conversation: a distributed messaging platform where producers publish to topics and consumers process at their own pace, with delivery guarantees you can build money movement on. Send ordinary messages for fire-and-forget events, transactional messages that commit or roll back with your local database transaction, ordered and FIFO messages for sequences that must not shuffle, and delayed messages that arrive seconds or days later on schedule. Consumers pull with long polling, filter by tag or SQL expression at the broker, and retry failures through built-in retry queues and dead letter queues instead of losing work. Clusters scale by adding brokers, while Controller mode elects broker replicas automatically so a failed node stops being a page. The Proxy component speaks gRPC with modern multi-language clients and adds POP consumption, where messages become invisible while processed and reappear if the consumer never acknowledges. Tiered storage offloads cold messages to cheaper object storage while hot data stays on local disk, and RocketMQ Streams, Connect, and an MQTT bridge extend the same cluster into stream processing, data integration, and device messaging. Lite Mode trims subscription overhead for AI workloads, and the separate RocketMQ Dashboard gives operators a web console for topics, consumers, and message tracing. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.