Office 365 Groups

docs.microsoft.com
Office 365 groups and Microsoft Teams - Link

Microsoft Tech Community -
Office 365 Groups - Link

Support - 
Office 365 Groups - Link

What's new -
Office 365 Groups - Link

End user training - videos
Unite your team with Groups in Outlook - Link

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Unofficial Resources - Info, Tips and Tricks

An everyday guide to Office 365 Groups - Link