Pub/Sub, or Publish/Subscribe messaging, is an asynchronous communication model that enhances system scalability and flexibility by decoupling data producers, known as publishers, from consumers, called subscribers. This model allows publishers to send messages to multiple subscribers through topic-based channels without needing to know their identities, enabling real-time data streams with low latency. Pub/Sub is particularly useful in applications requiring scalable, on-demand communication, such as IoT, telemetry, and serverless computing, and is implemented in systems like Google Cloud Platform and Amazon Web Services. While it offers significant advantages in dynamic scaling and workload distribution, it also faces challenges such as potential message delivery failures and instability during quick scaling, which can be mitigated with message brokers and additional parameters. PubNub, a real-time communication platform, exemplifies the effective implementation of Pub/Sub, providing global scalability and high reliability for applications requiring real-time data delivery.