Azure AD Connect is a software tool used to connect an existing on-premises environment to Azure AD and maintains the synchronization of objects from both environments (Users & Computers).
Before we start this tutorial, make sure that you already have an Azure AD tenant set up ahead of time. Check this link from a previous article to see how it's done.
To get started, download the tool from the URL below and then install it on the Primary domain controller in your on-premises environment and make sure that you are logged in with an account with Active Directory Domain Administrator permissions.
Then we insert the credentials of the Global administrator of Azure AD, as shown below.
On the next page, we insert the credentials of the Domain Administrator of our on-premises environment.
Eventually, we shall be presented with the sign-in configuration page. If you have a custom domain already setup, then the UPN suffixes will match your on-premise environment. For my case, this is a test environment, and hence I don't have a publicly registered domain attached to my on-premises Active Directory, so I will click the check box to continue as it is. It shouldn't be a problem. You can also do this after your domain registrar has verified your domain.
The last page should appear as something like this and then click install.
The Installation and synchronization process can take up to about 5 - 10 minutes depending on the size of Active directory objects you have in your on-premises environment, so grab yourself a cup of coffee.
Next, we can be able to see our users in the portal. I had only one user and can confirm that from the source column, which shows Windows Server AD on Peter Trizzy Matovu.
That's it, and we are done connecting our on-premises Active Directory to Azure AD in 5 simple steps.