The demand for realtime digital experiences is growing rapidly as users increasingly expect immediate updates and interactions from their favorite apps and websites. To meet this expectation, businesses are focusing on incorporating realtime features into their digital products. Key capabilities needed to engineer realtime experiences include low-latency messaging, message ordering and delivery guarantees, message history/persistence, message interactions, presence, multi-protocol support, and robust security. Realtime use cases range from chat applications and data broadcasting to data synchronization, multiplayer collaboration, notifications, and location tracking. Businesses can choose between building and managing realtime infrastructure in-house or offloading this responsibility to a specialized provider like Ably, which offers versatile APIs for developing powerful realtime apps at scale.