Office 365 is one of Microsoft's most popular cloud offerings, a low-cost service that people subscribe to in order to access various Microsoft services and software. It is the replacement of Microsoft's Business Productivity Online Suite (BPOS), Microsoft's previous cloud offering. It is free or super-low-cost, depending on the subscription, for 501(c)3 nonprofits and accredited educational institutions.
Office 365 is securely accessible anywhere with a supported device and an internet connection, and is independently verified to comply with regulations such as FedRAMP, FISMA, HIPAA, ISO 27001, EU, and others, with over 900 controls that enable keeping compliant never-changing industry standards. Office 365 has a financially backed guarantee of 99.9% uptime.
As such, Office 365 is constantly being updated due to customer feedback and Microsoft's desire to offer evergreen and best-in-class services. Due to this, they are constantly updating and improving the service, as well as offering new services.