Different to AWS Lambdas and Google Cloud Functions, Azure Functions supports the concept of bindings. Bindings are powerful addition to a serverless framework and makes FaaS even more serverless by abstracting datasources and sinks from the function itself.
Azure Functions also has support custom bindings, which allows FaaS Authors to implement their own datasource/sink. Creating a custom binding is very easy and straight forward, but has also a few pitfalls.