What is Microsoft Teams?

Microsoft Teams is the chat, meetings, calling, and collaboration hub of Microsoft 365. People often describe it as "Slack plus Zoom plus a file workspace" and that's a fair starting point — but Teams is wired more deeply into the rest of Microsoft 365 than that comparison suggests, and the depth is what makes it either the natural choice or a compliance headache depending on how it's run.

Where Teams fits

Teams sits at the centre of the Microsoft 365 collaboration story. It is the primary UI for chat, video, telephony, and increasingly the surface where Microsoft launches new collaboration features. Behind every team is a Microsoft 365 Group which provisions a shared mailbox, a SharePoint site, a OneNote notebook, and a Planner plan; every chat runs on Azure Communication Services; every meeting is stored in a user's OneDrive or the team's SharePoint; every call is routed through the same identity and CA policies as the rest of Microsoft 365. Teams is not a standalone product — it is a coordinated view onto the wider platform.

In the market, Teams competes with Slack, Zoom, Google Workspace, Cisco Webex, and (for telephony) Cisco Webex Calling, RingCentral, 8x8. It wins on the Microsoft 365 integration angle — Copilot, Exchange, SharePoint, Entra ID — and on the fact that for most Microsoft 365 customers, adding Teams costs nothing extra beyond the licence they already hold.

What Teams combines

At its core, Teams gives users:

Chat. One-to-one and group messages, with threads, reactions, mentions, and persistent history. Cross-tenant chat (Teams Connect) lets a user chat with someone in a different tenant using their own identity — the modern replacement for external accounts and email threads.

Teams and channels. A team is a group of people; channels are topic-based spaces inside it where conversations and files stay together. Standard channels are visible to all team members; private channels are restricted subsets; shared channels (Teams Connect) can invite people from outside the tenant into a single channel without adding them to the whole team. Shared channels are the most modern pattern for cross-org collaboration.

Meetings and calls. Scheduled or instant video meetings, screen sharing, recordings that land in the meeting organiser's OneDrive with a transcript, background effects, together mode, and up to 1,000 attendees in a standard meeting (10,000+ in a webinar or town hall). Copilot in meetings provides real-time and post-meeting summaries.

Telephony. With a Teams Phone licence, Teams becomes a full PBX with external phone numbers. Direct Routing, Operator Connect, and Microsoft Calling Plans are the three options for connecting Teams Phone to the PSTN — see the Teams Phone deep-dive for the trade-offs.

Files. Every team gets a SharePoint site behind the scenes; the files dropped into a channel live there. Personal 1:1 chat files sit in the sender's OneDrive.

Apps and tabs. Pinned access to Planner, OneNote, Power BI, Loop components, Approvals, Shifts, Bookings, third-party apps (Salesforce, ServiceNow, Zoom bridging), and custom-built apps. The app store governs which third-party apps are available; the admin center allows or blocks per user.

How it fits with the rest of Microsoft 365

Behind every team is a Microsoft 365 Group, which automatically provisions a shared mailbox, a SharePoint site, a OneNote notebook, and a Planner plan. When you open a file in a channel, you're really opening it from SharePoint. When you @mention someone, you're using their Microsoft Entra ID identity. Permissions cascade from there.

That cascade is the reason governing Teams sprawl is really about governing groups, sites, and files. Every new team is a new SharePoint site, a new mailbox, and (potentially) a new set of guest members. Left un-governed, a mid-sized tenant grows tens of thousands of teams in a few years, most of them stale, many with over-shared files. Team creation controls, expiration policies, sensitivity labels, and the SharePoint Advanced Management lifecycle features are the operational toolkit for keeping the estate healthy.

Copilot in Teams

Copilot in Teams touches chat (summarise a long conversation, find a decision from a thread), meetings (real-time summary during the meeting, post-meeting recap with action items and speaker attribution), and calls (call summary and post-call notes). Meeting Copilot is the flagship feature that most changes user behaviour — the ability to catch up on a meeting you missed by reading a Copilot-generated summary is a genuine productivity lift.

Copilot in Teams requires the Microsoft 365 Copilot licence ($30/user/month at 2026 pricing) on top of an eligible Microsoft 365 plan. Teams Premium adds intelligent recap and translated captions for meetings that don't have Copilot; the two products overlap but are not the same.

What Teams replaced

Teams replaced Skype for Business as Microsoft's communications client; the last on-prem Skype for Business Server is at end-of-support and the Skype consumer app has been retired. Teams has also absorbed most of what people previously used Yammer for — Yammer became Viva Engage, which is now surfaced primarily through Teams. SharePoint team sites for socialisation still exist but are no longer the primary daily surface; users live in Teams and reach into SharePoint when they specifically need a file or a page.

New collaboration features from Microsoft — Loop, Copilot integration, Approvals, Shifts, Bookings, Places — ship through Teams first. Teams is the strategic surface; new products either live inside it or are surfaced through it.

Common operational patterns

Three that come up in nearly every mid-size and large tenant:

External and guest access. Guests from other tenants can be added to teams (guest access), and shared channels let people participate without becoming guests (Teams Connect). The two patterns coexist; guest access is the older mechanism, shared channels the newer and more modern. Governance policy has to decide which to use where and enforce it through Conditional Access.

Sensitivity labels on teams. A sensitivity label applied to a team drives the underlying group and SharePoint site's protection settings — external sharing, guest access, unmanaged-device access, downloadability. Labels are the primary tool for enforcing collaboration policy at scale; without them, per-team configuration drifts and audit becomes impossible.

Meeting policies. Meeting policies control who can bypass the lobby, who can record, who can present, whether transcription is on by default. Global policies work for most; policy exceptions for exec staff, board meetings, and regulated conversations are common.

Licensing

Teams is included with almost every Microsoft 365 SKU — Business Basic, Business Standard, Business Premium, E1, E3, E5, F1, F3, plus most academic and government variants. There is a standalone Teams Essentials for very small businesses without an M365 subscription.

Add-ons that layer on top:

Teams Premium — meeting features (intelligent recap without Copilot, meeting templates, watermarks, custom meeting branding, advanced webinars, virtual appointments). Priced per user per month.

Teams Phone — the PBX. Priced per user per month, plus PSTN connectivity through Direct Routing, Operator Connect, or Microsoft Calling Plans.

Teams Rooms Pro — advanced management for meeting-room devices. Priced per room per month.

Microsoft 365 Copilot — includes Copilot in Teams for meetings, chat, calls, and Teams chat surfacing across the productivity apps.

The short version

Teams is the collaboration hub of Microsoft 365 — chat, meetings, telephony, and files, all on top of the same identity, storage, and compliance stack as the rest of the platform. It replaced Skype for Business, absorbed most of Yammer, and is the strategic surface for new Microsoft 365 features. Running it well is mostly about governing the underlying Groups and SharePoint sites, and about layering the right add-ons (Premium, Phone, Rooms, Copilot) on top of the base licence.