Microsoft Azure is a cloud computing platform created by Microsoft which developers and IT professionals use to build, deploy and manage applications through their global network of datacentres.
To know more about azure have a look at https://www.edureka.co/blog/microsoft-azure-tutorial
You can sign up with your Microsoft account or you can use your GitHub account and take your code all the way from repositories to deployment.
Azure App Service enables you to build and host web apps, mobile back ends, and RESTful APIs in the programming language of your choice without managing infrastructure.
It offers auto-scaling and high availability, supports both Windows and Linux, and enables automated deployments from GitHub, Azure DevOps, or any Git repo.
For further details refer https://docs.microsoft.com/en-in/azure/app-service/