[13] On August 29, 2007, Microsoft purchased Parlano and its persistent group chat product, MindAlign.

[14] On March 4, 2016, Microsoft had considered bidding $8 billion for Slack, but Bill Gates was against the purchase, stating that the firm should instead focus on improving Skype for Business.

[15] After the departure of Lu later that year, Microsoft announced Teams to the public as a direct competitor to Slack at an event in New York on November 2, 2016,[11][16] and was launched worldwide on March 14, 2017.

[20] ZDNET reported that the companies were not competing for the same audience, as Teams, at the time, did not let members outside the subscription join the platform, and small businesses and freelancers would have been unlikely to switch.

[30][31] It announced a "Walkie Talkie" feature in early 2020 that uses push-to-talk on smartphones and tablets over Wi-Fi or cellular data,[32] for employees who speak with customers or run day-to-day operations.

[32] On March 19, 2020, Microsoft announced Teams had hit 44 million daily users,[33] mostly due to the COVID-19 pandemic.

[7] In July 2020, Microsoft shut down its video game livestreaming service Mixer, and announced that its developers would be working some of its technology into Teams.

[37] Microsoft Teams is a web-based desktop app, originally developed on top of the Electron framework which combines the Chromium rendering engine and the Node.js JavaScript platform.

[50] Teams for Education allows admins and teachers to set up groups for classes, professional learning communities (PLCs), staff members, and everyone.

[52] Connectors include Mailchimp, Facebook Pages, Twitter, Power BI and Bing News.

VoIP and video conference clients based on SIP and H.323 need special gateways to connect to Microsoft Teams servers.

[66] In July 2023, the EU Commission opened an anti-trust investigation into the possibility that Microsoft unfairly used its office suite market power to increase sales of Teams and hurt its competitors.