Slack, on the other hand, hasn't proven as popular with investors, even though its service that publicly launched in 2014 is being increasingly used by companies and government agencies looking for more nimble alternatives than email. Microsoft for one has developed its own thriving online suite of services, known as Office 365, which includes a Teams messaging app that includes many of the same features as Slack's 6-year-old application. But software as a service has become an industry standard that has turned into a gold mine for longtime software makers.

Salesforce's outspoken founder and CEO Marc Benioff hailed the 'cloud computing' concept as the wave of the future to much derision initially. The San Francisco company was one of the first to begin selling software as a subscription service that could be used on any internet-connected device instead of the more cumbersome process of installing the programs on individual computers.

The acquisition, announced Tuesday, is by far the largest in the 21-year history of Salesforce. Business software maker Salesforce will acquire work-chat service Slack for $27.7 billion in a deal aimed at giving the two companies a better shot at competing against longtime industry powerhouse Microsoft.

Salesforce purchase slack