The default team chat app for most companies — channels, DMs, and huge third-party app support.
Visit SlackSlack won the workplace-chat category early and still leads on integration breadth — almost every SaaS tool has a Slack connector. The tradeoff is notification overload at scale; teams need real channel discipline or it becomes noise. Huddles (voice/video) are solid for quick syncs but not a full video-conferencing replacement.