Skype is Microsoft's free video-calling app that was once a major telecommunications industry disruptor, but has since fallen out of popular use.Aytac Unal/Anadolu Agency/Getty ImagesSkype is a free video-calling platform that Microsoft acquired for $8.5 billion over a decade ago.Skype was once the go-to video-calling app and telecommunications industry disruptor.But now, Skype has faded out of popular usage in favor of platforms like Zoom and Microsoft Teams.Skype, a telecommunications platform currently owned by Microsoft, became ubiquitous in the early 2000s, at one point accounting for up to 40% of all international calls.While Skype has since lost some of its audience to Microsoft Teams — particularly in the business context — and a significant portion of its market share to Zoom, it still maintained an average of 40 million daily users as of 2020.Founded in 2003 by Swedish entrepreneur Niklas Zennström and Danish entrepreneur Janus Friis, Skype held its first public trial in August of that year.