Outlook

Outlook is Microsoft's email and calendar client. It comes in several editions: Outlook for Windows (a new browser-based client now replacing the classic Win32 version), Outlook for Mac, Outlook on the web (outlook.office.com), and Outlook mobile for iOS and Android. All of them talk to Exchange Online — and to other mail systems via IMAP, POP, and Microsoft account integrations. Beyond mail and calendar, Outlook surfaces contacts, tasks (via Microsoft To Do), and Teams meeting scheduling, and it's where many users live for hours a day. Add-ins extend it with custom panes from line-of-business systems.