SharePoint is the intranet solution from Microsoft.

SharePoint Online

SharePoint online (SPO) is usually included in your Microsoft 365 subscription, but can also be purchased directly. SharePoint Online has the advantage that there is no need to operate a separate server, but it lacks the customization options of a self-hosted installation of SharePoint.
Although SharePoint Online is limited to core functions in the area of collaboration, document and content management as well as hosting and synchronization of files, it receives updates and new functions much more frequently.


Source: https://de.wikipedia.org/wiki/SharePoint