Announcing the general availability of Durable Functions functionality in Azure Functions. Durable Functions is an Azure Functions extension for building long-running, stateful function orchestrations in code using C# in a serverless environment. This allows developers to implement a lot of new scenarios which were not possible earlier, including complex chaining scenarios, fan in/fan out patterns, stateful actors, and scenarios with long callbacks.
This feature has widely been acknowledged as a differentiator for Azure Functions and is not available in any of the competing serverless FaaS services.
Source: Azure Roadmap