Microsoft Office 365 is a cloud-based subscription service that provides access to various Microsoft productivity tools such as Word, Excel, PowerPoint, Outlook, and OneDrive. It allows users to create, edit, and collaborate on documents, spreadsheets, and presentations in real-time from any device with an internet connection. Office 365 also offers additional services such as email hosting, online storage, and communication tools like Skype for Business. This subscription service provides regular updates and new features to enhance productivity and efficiency for businesses and individuals.