SharePoint Online, as part of Office 365, is continually improved. The SharePoint Help Center is also continually updated with the latest changes. Below are some other resources on what's new.
The Office Blog covers updates to Office 365. Also, read how the updates enable new scenarios for others.
The SharePoint category filters the Office Blog to posts about SharePoint only.
Read the SharePoint Blog, in the Microsoft Tech Community, to learn best practices, news, and trends directly from the SharePoint team.
Microsoft 365 Roadmap
The Microsoft 365 Roadmap is the official site for Microsoft 365 updates and changes, including Office 365. In addition to listing updates available now, the roadmap also includes information about improvements that are coming soon.
For Admins Only
Administrators and IT Professionals should read Stay on top of Office 365 changes which covers update messages delivered through the Office 365 Admin Center.
Update Nov 8, 2018