Office 2019 is sold as a one-time purchase, which means you pay a single, up-front cost to get Office apps for one computer. One-time purchases are available for both PCs and Macs. However, there are no upgrade options, which means if you plan to upgrade to the next major release, you'll have to buy it at full price.

Microsoft 365 is a subscription that includes the most collaborative, up-to-date features in one seamless, integrated experience. Microsoft 365 includes the robust Office desktop apps that you’re familiar with, like Word, PowerPoint, and Excel. You also get additional online storage and cloud-connected features that let you collaborate on files in real time. With a subscription, you'll always have the latest features, fixes, and security updates along with ongoing tech support at no extra cost. You can pay for your subscription on a monthly or yearly basis, and the Microsoft 365 Family plan lets you share your subscription with up to five members of your household, for a total of six users, and use your apps on multiple PCs, Macs, tablets, and phones.

Microsoft 365 is compatible with PC, Mac, Android, and iOS. See system requirements for compatible versions of your devices and for other feature requirements

No. Microsoft 365 apps are tailored for each platform and each operating system. The apps available for Mac users and the specific features included may be different from those available for PC users. With Microsoft 365, you can be flexible. You’re not limited to exclusively Mac or exclusively PC, so you can transition across devices

Internet access is required to install and activate all the latest releases of apps and services included in all Microsoft 365 subscription plans. Note that if you’re an existing subscriber, you don’t need to reinstall or purchase another subscription.

For Microsoft 365 plans, Internet access is also needed to manage your subscription account, for example to install Office apps on other PCs or to change billing options. Internet access is also required to access documents stored on OneDrive, unless you install the OneDrive desktop app.

You should also connect to the internet regularly to keep your version of Microsoft 365 up to date and to get automatic upgrades. If you don’t connect to the internet at least every 31 days, your apps will go into reduced functionality mode, which means you can view or print your documents but can’t edit the documents or create new ones. To reactivate your apps, simply reconnect to the internet.

You don’t need to be connected to the internet to use the Office apps, such as Word, Excel, and PowerPoint, because the apps are fully installed on your computer.