Skype for Business is a communication and collaboration tool that enables users to connect with colleagues, customers, and partners in real-time. With Skype for Business, you can hold online meetings, share documents, and collaborate on projects with ease. It also provides a secure platform for
From Wikipedia
Skype was a proprietary telecommunications application operated by Skype Technologies, an acquired division of Microsoft, best known for IP-based videotelephony, videoconferencing and voice calls. It also had instant messaging, file transfer, debit-based calls to landline and mobile telephones, and other features. It was available on various desktop, mobile, and video game console platforms.