Real-time technology facilitates the instantaneous exchange of data, significantly enhancing user experiences in applications such as instant messaging, live streaming, and navigation. Real-time applications handle data transmission in milliseconds, enabling activities like live updates and notifications in platforms like Uber, Zoom, and WhatsApp. The architecture supporting these systems includes patterns like Pub/Sub and event-driven models, which ensure high throughput and low latency. Transport protocols, such as WebSockets and HTTP/2, play a critical role in maintaining performance and reliability. State management and synchronization are vital for maintaining consistency across distributed systems, using methods like Conflict-free Replicated Data Types (CRDTs) and Operational Transformation (OT). Message brokers like Apache Kafka and PubNub offer solutions for managing real-time data flows, with PubNub providing a scalable infrastructure for developers to build real-time interactivity without the complexity of maintaining the underlying systems. While all real-time applications are online, not all online applications function in real-time, as seen in examples like e-commerce sites that require manual refreshes to update content.