Azure Functions, a service from Microsoft that offers developers a serverless architecture to run their code on, is now generally available. The news comes from a blog post on the official Azure blog, which also wraps up some of the history of Functions' development and showcases all of the features that have been baked into the service leading up to this point.
— Microsoft Azure (@Azure) November 15, 2016
Functions differentiates itself from competitors by offering developers a service that lets your payment scale with the amount of demand that you're experiencing.
Put simply, if your code is running for a while, you'll be charged for the time that it was run. The pricing makes sure that people won't be charged disproportionately, and makes it more user-friendly.
If you aren't totally sold on Azure Functions yet, you can give it a shot risk-free. Just follow the link in the Azure blog post, and you'll be able to try Functions for one hour without even submitting a credit card.