Here’s just one example:
Each M365 Teams Team creates an M365 Group which creates a SharePoint site and Exchange mailbox. Teams channel files are stored in that SharePoint site. Teams channel messages are stored in the Exchange mailbox.
Private files dropped in Teams are stored in OneDrive (rebranded SharePoint). Private Teams messages are stored in the sender and recipients’ Exchange mailboxes.
M365 is SharePoint and Exchange. EVERYTHING is built on top.
EDIT: changed ‘individual’ to ‘sender and recipients’