'Cortana, Open Alexa,' Amazon Says. And Microsoft Agrees.

The crowded pack of voice-controlled digital assistants -- Apple's Siri, Google Assistant, Amazon's Alexa and Microsoft's Cortana -- are good at numerous things. They can help people play music, set up calendar appointments and check the weather. They can even get two rival tech executives, Jeff Bezos of Amazon and Satya Nadella of Microsoft, to join hands in a rare partnership. For the past year, the two companies have been coordinating behind the scenes to make Alexa and Cortana communicate with each other. The partnership, which the companies plan to announce early Wednesday, will allow people to summon Cortana using Alexa, and vice versa, by the end of the year.