Microsoft is pushing their collaboration solution “Teams” further into the market by providing a free version for smaller companies.
Until now, Microsoft Teams was only available for customers owning an Office 365 Business or Enterprise plan. There was no option to get only Teams and skip the other tools like Exchange, SharePoint and OneDrive for Business. In comparison to the competitor Slack, that made Microsoft Teams quite pricy.
With the free option, Microsoft now provides a competitive solution and could get Slack customers to switch to Teams.
Modern Workplace Blog 