The following are 5 Top Sites for Microsoft 365 Documentation:
Microsoft 365 Documentation:
https://docs.microsoft.com/en-us/microsoft-365/?view=o365-worldwide
SharePoint
Documentation:
https://docs.microsoft.com/en-us/sharepoint/
MS Teams Admin Documentation:
https://docs.microsoft.com/en-us/microsoftteams/
SharePoint PowerShell:
https://docs.microsoft.com/en-us/powershell/sharepoint/?view=sharepoint-ps
MS Teams PowerShell:
https://docs.microsoft.com/en-us/MicrosoftTeams/teams-powershell-overview
