Workplace messaging owned by Salesforce. Channels, threads, Slack AI, and Slack canvases; the de-facto workplace chat layer.
From Wikipedia
Slack is a cloud-based team communication platform developed by Slack Technologies, which has been owned by Salesforce since 2021. Slack uses a freemium model. Slack is primarily offered as a business-to-business service, with its user base being predominantly team-based businesses while its features are focused on business administration and communication.