Office 365 is a suite of products and services by Microsoft. It includes all the traditional Microsoft Office tools (Word, Excel, PowerPoint, OneNote, Access and Outlook), plus a series of new tools and online services.
All Office 365 subscriptions come with Microsoft OneDrive, that allows users to store files as well as other personal data like Windows settings or BitLocker recovery keys in the cloud. 1 TB of storage per user.
Depending on the subscription it also includes:
Email hosting with 50 GB mailbox and custom email domain address with Exchange
Web versions of Word, Excel, and PowerPoint
Company-wide intranet and team sites with SharePoint
Skype – Online meetings and video conferencing for up to 250 people
Hub for teamwork to connect your teams with Microsoft Teams
Collaborate across departments and locations with Yammer
and many more services (Microsoft Connections, Microsoft Listings, Outlook Customer Manager, Microsoft Invoicing, Microsoft Bookings, MileIQ, Business center, Microsoft Planner and StaffHub)