Slack is a cloud-based set of proprietary team collaboration tools and services, founded by Stewart Butterfield.
Slack began as an internal tool used by their company, Tiny Speck, in the development of Glitch, a now defunct online game.
The name is an acronym for "Searchable Log of All Conversation and Knowledge".
Slack was launched in August 2013. In January 2015, Slack announced the acquisition of Screenhero.