Slack

Slack gives your team the power and alignment you need to do your best work.

Snippet from Wikipedia: Slack (software)

Slack is a cloud-based set of proprietary team collaboration software tools and online services, developed by Slack Technologies headquartered in San Francisco, California after fully relocating its headquarter from Vancouver, British Columbia in 2017. Slack began as an internal tool for Stewart Butterfield's company Tiny Speck during the development of Glitch, an online game. "Slack" is a backronym for "Searchable Log of All Conversation and Knowledge."