Microsoft Teams
Description
When Slack was launched in 2013, it created a new category: the team chat workspace, where persistent channels replaced email threads for internal communication. Microsoft saw Slack amass tens of millions of users inside Fortune 500 companies and saw the threat directly. In 2016, Qi Lu, who was then executive vice president of Applications and Services, lobbied internally to buy Slack for about $8 billion. Bill Gates was against the acquisition and argued that Microsoft should build its own competing product rather than purchasing one. That decision influenced the next decade of enterprise software.
Teams was announced by Microsoft on November 2, 2016, at an event in New York City. Slack responded with a full page advertisement in the New York Times welcoming the competition — a move that acknowledged the seriousness of Microsoft’s entry into a market Slack had built. Teams were launched globally on March 14, 2017. Because Microsoft bundled Teams into existing Office 365 subscriptions at no extra cost, every organization that was already paying for Microsoft’s productivity suite suddenly had access to a Slack competitor without having to make any new purchasing decision.
Microsoft Teams integrates persistent chat channels, video and audio calling, file storage, calendar integration and a wide app ecosystem in one workspace. It’s based on the rest of Microsoft 365 — SharePoint stores files shared in Teams, Exchange handles calendar and meeting scheduling, Azure Active Directory manages identity and access — making it both an extension of Microsoft’s existing infrastructure and the primary interface through which many organizations now access that infrastructure. In 2023, Microsoft had 320 million monthly active users. Skype, Microsoft’s older consumer video calling service, was retired on May 5, 2025, with Microsoft directing remaining users to Teams.
HISTORY AND BACKGROUND
Microsoft’s journey to Teams began long before 2016. In 2007, Microsoft bought Parlano, a company whose product, MindAlign, provided team chat capabilities. Microsoft sold MindAlign the same year it acquired it — not for the application itself, but to absorb Parlano’s underlying chat technology into Office Communicator, its enterprise unified communications client. Office Communicator eventually evolved into Microsoft Lync, and in 2014, Lync was rebranded as Skype for Business, linking Microsoft’s enterprise communications product to the consumer brand Microsoft had bought in 2011 for $8.6 billion.
Skype for Business was responsible for voice, video and instant messaging for large organizations, but it was a separate application that was disconnected from the document collaboration and file sharing tools that organizations used in Office 365. When Slack proved that workers wanted a persistent, channel-based workspace and not a session-based communications tool, Microsoft’s existing product lineup had no direct answer.
Following the Gates decision to build instead of buy, Microsoft put together a development team and built Teams in about a year. The November 2016 preview included channel-based chat, Office 365 file integration, voice and video calls using Skype for Business infrastructure, and a tab system for embedding third-party applications. The product was made available to the general public on March 14, 2017, spearheaded by corporate vice president Brian MacDonald.
Microsoft’s strategy right from the beginning was displacement through bundling. Rather than charging for Teams separately, Microsoft included Teams in Office 365 Enterprise and Business suite subscriptions. Any organization paying for Office 365 — and by 2016, Office 365 had 85 million monthly active users — could deploy Teams without any additional budget approval. This distribution advantage was more decisive than any individual feature.
In September 2019, Microsoft announced that it would be retiring Skype for Business on July 31, 2021, effectively unifying its enterprise communications strategy around Teams. The adoption of remote work arrangements was accelerated by the beginning of the Covid-19 pandemic, which forced many to work remotely in March 2020. On March 19, 2020, Microsoft reported that it had 44 million daily active users. As of April 2020, Teams users had 4.1 billion meeting minutes in a single day. The pandemic squashed what might have been years of gradual adoption into weeks.
The European Union launched antitrust probes into Teams bundling with Microsoft 365. In response, Microsoft announced in October 2023 that it intended to separate Teams from Microsoft 365 in European markets, selling it as a standalone product. In April 2024, Microsoft expanded that separation worldwide, introducing Microsoft 365 without Teams at a lower cost alongside Teams as a standalone purchase. The European Commission in July 2024 closed its investigation after Microsoft agreed to further interoperability measures.
Microsoft has been integrating its Copilot AI assistant into Teams step by step since 2023, adding AI-generated meeting transcripts and summaries, message drafting assistance, and channel thread recaps. Skype was completely shut down on May 5, 2025.
KEY FEATURES
Chat and Channels
Teams organizes communication in two main structures. Channels are persistent, topic-based conversation spaces within a team — a workspace shared by a defined group of people. Members post messages in channels, reply to messages in threaded conversations, share files, and mention specific colleagues. Each channel is a complete history, so it is searchable and available to members who join in later. Private channels are restricted to a subset of team members. Shared channels allow access to individuals outside the organization without needing them to change tenants. Standard chat is a direct messaging — one-on-one or group chat outside the channel structure, appropriate for informal exchanges or quick coordination.
The 2025 interface update combined chat and channels into one navigation pane, where users can filter by unread messages, mentions, and specific people or teams. Custom sections allow individuals to group conversations based on project or priority. Thread summaries, which are available with a Microsoft 365 Copilot license, summarize long channel discussions into key takeaways without having to scroll through the entire history.
Video and Audio Meetings
Teams deals with video conferencing from two-person calls to large-scale events. Standard meetings support up to 1,000 participants for interactive sessions, and up to 10,000 attendees for view-only overflow. Each participant can share his or her screen, a particular application window, or individual browser tabs. Background blur and custom virtual backgrounds reduce visual distractions. Noise suppression filters out keyboard sounds, background conversations and environmental noise from audio feeds.
Meeting recordings capture video, audio, and shared content and store automatically in OneDrive or SharePoint. Live transcription produces text in real time during meetings, attributed to individual speakers when users have set up voice profiles. After the meeting, the transcript feeds into the meeting recap, which includes a searchable record of what was said, timestamps and any files shared.
Breakout rooms divide meeting participants into smaller groups for focused discussion and then bring them back to the main session on the command of the host. Front Row layout with the speaker and shared content in the center of the screen, with other participants’ video feeds below, is designed for hybrid meetings where some attendees are in a conference room and others are participating remotely. Together Mode puts all participants in a shared virtual environment — an auditorium, a classroom, a cafe — as an alternative to the standard grid of individual video feeds.
Webinars and Town Halls
Teams supports structured large-scale events using two dedicated formats. Webinars support up to 1000 attendees with registration management, attendee reporting, and presenter controls that limit what attendees can do during the session. Town halls scale to 10,000 attendees and have production-focused features such as managed Q&A queues, live captions translated into multiple languages, and green room access for presenters to prepare before the session goes live. Teams Live Events, the predecessor format, managed broadcasts of up to 10,000 participants, and replaced Skype Meeting Broadcast.
Teams Phone (Calling)
Teams Phone extends Teams to be a complete business phone system, replacing traditional PBX infrastructure. Organizations can assign phone numbers to users, route calls through auto-attendants and call queues, and handle transfers, holds, and conference calls from inside the Teams client. Direct Routing connects Teams to existing telephony infrastructure using a certified Session Border Controller so organizations can retain existing carrier contracts. Operator Connect works with carriers to offer managed PSTN connectivity directly in the Teams admin center. Teams Phone Mobile lets a user’s mobile carrier number and their Teams number be one identity, and routes calls to whichever device is active.
Copilot offers AI-powered call recaps for Teams Phone calls after the call is over, bringing up a summary, key points discussed, and recommended follow-up actions in a side panel in the Calls app. As of April 2024, Microsoft supports Teams Phone with a financially guaranteed 99.999% uptime SLA.
File Storage and Collaboration
Every team in Teams has a corresponding SharePoint site behind it. Files shared in a channel are uploaded to the document library of the SharePoint site. Files sent in chat are stored in the sender’s OneDrive. Either way, files can still be accessed from the Teams Files tab and from SharePoint directly. Word, Excel and PowerPoint documents open and coedit within Teams without leaving the application, with changes syncing in real-time across all editors. OneNote notebooks are attached to teams as tabs, providing groups with a shared space for notes, documentation, and reference material. Loop components — live, editable blocks of content — embed directly in chat messages and update everywhere they appear when anyone edits them.
Tabs, Apps, and Integrations
Each channel and chat can have tabs pinned at the top of the conversation: documents, websites, dashboards, or applications that team members need frequent access to. Microsoft AppSource has thousands of third-party integrations for project management tools like Asana, Jira, and Trello, customer relationship platforms like Salesforce, developer tools from GitHub and Azure DevOps, and productivity services from Adobe, Atlassian, and SAP. Incoming webhooks allow external services to send automated messages into channels. Power Automate integrates Teams with workflows across other Microsoft and third-party services without the need for custom code.
Copilot Studio enables organizations to create custom AI agents that participate in Teams meetings and chats, answer questions, keep track of action items, and automate repetitive tasks. Channel Agents, introduced in 2025, bind to individual channels and use the history of the conversations, shared files, and meeting content there as a domain-specific knowledge source for the team.
Calendar and Scheduling
Teams integrates directly with Outlook calendars via Exchange. Meeting invitations from Teams are received in Outlook, and meetings from Outlook are received in Teams. The Teams calendar provides daily and weekly views, meeting details, including the join link and attached files, and allows users to schedule new meetings using the scheduling assistant, which checks the availability of all invited participants. The Bookings app in Teams allows individuals or teams to publish scheduling pages that outside contacts can use to schedule appointments, and confirmed bookings are routed directly into the Teams calendar.
Security, Compliance and Administration
Teams works within Microsoft’s enterprise compliance framework. Data in transit is encrypted using TLS, data at rest is encrypted in Microsoft’s datacenters. Organizations that have Microsoft Purview licenses can use retention policies, legal holds, and eDiscovery searches on Teams messages and files. Sensitivity labels from Microsoft Information Protection are inherited by meeting invitations and channel content, which limits sharing and applies access controls automatically.
Teams Premium adds meeting specific security features including Prevent Screen Capture which blacks out the meeting window when a participant tries to screenshot or record externally. Watermarking has the viewer’s email address embedded as a visible overlay on video feeds and shared content in meetings where hosts are presenting sensitive material.
The Teams admin center provides IT administrators with centralized control over user policies, meeting settings, calling configurations, device management, and app permissions. Policies apply at the user, group, or organization level and can be used to restrict which features certain populations can access — relevant for organizations that need to limit external communication or control which third-party applications appear in Teams.
Frontline Worker Features
Teams includes a set of capabilities aimed at workers who do not sit at a desk. Shifts is a scheduling tool that managers use to create and publish work schedules, which are viewed and responded to by employees from a mobile device. Walkie Talkie transforms a phone into a push-to-talk radio using Wi-Fi or cellular data, intended for workers in retail, manufacturing, healthcare and field service who need to communicate quickly by voice without a traditional phone call. Task management with Microsoft Planner integrates with Teams to assign, track and complete work items in the same workspace where the team communicates.
Microsoft Teams Rooms
Teams Rooms is a hardware and software solution that brings Teams meetings into physical conference rooms. Certified Teams Rooms devices — manufactured by Yealink, Logitech, Poly, Crestron, and others — are a combination of camera, microphone, display, and compute hardware with Microsoft’s Teams Rooms software. A room system connects to meetings using a single tap, displays the meeting agenda on an in-room display and automatically manages camera framing. Intelligent Speaker technology, available in select rooms, recognizes individual speakers during live transcription by comparing voice profiles enrolled in advance. Smart camera features dynamically choose the best camera angle in the case of multiple cameras covering the same room, so that remote participants can see whoever is speaking.
Note: Teams Phone features require a Microsoft 365 Business or Enterprise subscription with a Teams Phone license. Copilot features (meeting recaps, thread summaries, call summaries, message drafting) require a Microsoft 365 Copilot add-on license ($30/user/month). Teams Premium features (Prevent Screen Capture, watermarking, custom meeting templates) require Teams Premium add-on ($10/user/month).
