Hybrid authentication and Single Sign-On
Organizations have come a long way from an on-premises IT infrastructure since they started to roll out cloud-based Software as a Service (SaaS) applications such as Microsoft Office 365. Users usually do not want to keep track of several accounts and, as they already have a corporate account based on Windows Server AD, they usually also want to use that account for cloud-based authentications. Now, this is when Azure AD Connect comes into play.
Azure AD Connect is a directory replication service that helps you to synchronize existing user accounts from an on-premises Windows Server AD with Azure AD. This is a mandatory step because you can only grant access rights and licenses to cloud-based identities in Azure AD, not to on-premises accounts.
With Azure AD Connect, you have several options to provide a single sign-on experience to your users. In the following diagram, you can see a decision tree that helps you to decide which of them...