Using Server to Server S2S authentication to connect your application to Dynamics 365 - .Net MVC Web application as an example | Mohamed Mostafa's Blog
Microsoft has recently released a feature that allows your application to connect securely and seamlessly connect to Microsoft Dynamics 365 Online solutions. S2S authentication is now the standard way that apps registered on Microsoft AppSource use to access the Dynamics 365 data of their subscribers. I found this feature a great addition to help secure .Net MVC applications access to Dynamics 365.