Salesforce acquired Slack in December 2020 in what is touted to be the biggest acquisition in the software industry till date with the valuation of US$ 27.7 Billion.
Slack is a collaboration and instant messaging tool (i.e. an enterprise communication platform). It will fall in the category of products like Microsoft Teams, Google Hangouts Chat, Cisco Jabber, Workplace by Facebook and others. If you haven’t had a chance to look at Slack yet, here is an introductory video (2:33 minutes).