Skype for Business 

This application started as Lync in the first release of Office 365 and is different than Skype, which is the consumer service. With this service, each user has their own account where they can see the presence of people in their personal list and have the ability to instant message and schedule or initiate impromptu online meetings with audio or HD video conferencing for up to 250 participants. No more sharing meeting accounts! It also allows the host(s) to share surveys, polls, and whiteboards with the attendees, and attendees as well as the host(s) can share a meeting notebook or take notes on an individual basis via OneNote integration. Invited attendees do not have to have the Skype for Business application to participate in the meeting.

Skype for Business is included with the Business Essentials, Business Premium, E1, E3, and E5 plans, and were initiated after around 24 August 2018. Any plan initiated after this date will only have Microsoft Teams available, as Teams is replacing Skype for Business in purely cloud Office 365 tenants. Your organization will still have the ability to have a Skype for Business server on premises if desired and if the appropriate additional server (not Office 365) licenses are purchased and deployed. If you have an E5 plan, you may also get a phone number assigned to you from this service and have the ability to dial out and receive calls via this application.