DEEP DIVE: WHERE DO FILES IN TEAMS RESIDE ?

When you create a team in Microsoft Teams, it automatically provisions a Microsoft 365 Group, including:

• A SharePoint Online team site.
• A group mailbox and calendar in Outlook.
• Other connected services.

The Files tab in Teams channels provides a user-friendly interface to the associated SharePoint document library, ensuring seamless real-time synchronization of uploads, edits, deletions, and permissions.

Core Integration: Teams Channels and SharePoint Document Libraries

Standard (Public) Channels

• Every team connects to one primary SharePoint Online site via the Microsoft 365 Group.
• The default document library, Documents, stores all channel files.
• Each channel (including General) maps to a folder in the Shared Documents library (accessible via /Shared Documents/ in SharePoint).
  • General channel → Root of the library or /General/ folder (depending on creation timing).
  • Other channels (e.g., "Project Alpha") → Folder named after the channel (e.g., /Project Alpha/).
• Files uploaded to a channel's Files tab go directly into the corresponding folder in SharePoint.
• The Files tab in Teams embeds a view of this folder using SharePoint's file management capabilities.
• Changes sync bidirectionally and instantly:
  • Upload/edit in Teams → Reflects in SharePoint.
  • Upload/edit in SharePoint → Reflects in Teams Files tab.
• Permissions align with team membership: Team members gain access to the SharePoint site as owners or members, inheriting folder permissions.

Accessing the SharePoint Site from Teams

• In any channel's Files tab, click Open in SharePoint to navigate directly to the folder in the browser.
• This opens the full SharePoint interface for advanced features like versioning, metadata, or workflows.

Additional Tabs and Custom Libraries

• Teams allows adding custom tabs pointing to other SharePoint libraries, lists, or pages from the same site (or other sites).
• However, the default Files tab always links to the channel's folder in the main Documents library.

Private Channels

• Private channels restrict membership within a team.
• For isolation, each private channel creates a separate SharePoint site collection.
  • This site has its own storage quota (separate from the parent team's site).
  • Naming convention: Typically includes the private channel name (e.g., SPSiteName-PrivateChannelName).
  • Only private channel members access this site (parent team owners cannot access by default).
• Files in a private channel's Files tab store in this dedicated site's document library.
• Synchronization works identically: Bidirectional with the private site's library.
• Site collections remain hidden from the main team's SharePoint navigation for security.

Shared Channels

• Shared channels enable collaboration with external users or across teams.
• Files store in the host team's SharePoint site (similar to standard channels), but permissions manage access for external/shared members.

Personal Chats and Group Chats (Non-Channel)

• Files shared in one-on-one or group chats (not tied to a team channel) store in OneDrive for Business, not SharePoint.
  • The uploader's OneDrive hosts the file in a folder called Microsoft Teams Chat files.
  • A share link grants access to chat participants.
  • In Teams, these files appear in the chat's Files tab.
• Group chats without a team lack a dedicated SharePoint site.

Meeting Recordings and Other File Types

• Non-channel meetings (scheduled via chat or calendar): Recordings store in the organizer's OneDrive (in /Recordings/ folder).
• Channel meetings: Recordings store in the channel's Files tab → A Recordings folder in the corresponding SharePoint document library.
• Transcripts and other artifacts follow similar patterns.

Permissions and Governance Implications

• Team membership drives SharePoint site permissions:
  • Owners → Site owners.
  • Members → Site members (edit access).
• Guest users in Teams gain corresponding SharePoint access.
• Files inherit library/folder permissions, but manual breaks occur if needed.
• Admins manage storage quotas at the tenant level or per site (private channels count separately).
• Compliance features (e.g., retention policies, eDiscovery) apply via SharePoint/OneDrive.

Why This Architecture Matters

• No duplication — Teams acts as a frontend; storage remains in SharePoint/OneDrive.
• Unified experience — Users work in Teams while leveraging SharePoint's robust document management.
• Scalability and security — Group-connected sites enable advanced features like sensitivity labels and information barriers.

This design ensures Teams provides an intuitive file experience while relying on SharePoint's enterprise-grade document management backbone. For the most current details, check official Microsoft documentation, as features evolve.