Ably has introduced Annotations in its Pub/Sub platform, a feature designed to enhance realtime streams with structured, contextual data. Annotations allow users to add layers of information to messages, such as emojis, read receipts, and custom tags, making them versatile for applications like collaborative chat, IoT sensor streams, live trading data, and more. This feature offers flexibility with various annotation types, including total, distinct, unique, multiple, and flag, each providing different behaviors and use cases, such as tracking aggregate counts, enabling multiple reactions, or flagging messages for moderation. Annotations extend beyond chat, offering applications in live sports data, IoT, live trading streams, and logistics, turning data streams into interactive tools. To use annotations, developers need to enable the mutableMessages channel rule in the Ably Pub/Sub API, and the feature is currently supported in JavaScript, Cocoa, and Java SDKs, with plans for further expansion.