You have fast, unlimited internet and only need Office on one computer. Pro Tip: After a successful offline installation, keep the installer file on a USB stick labeled "Office – [Version]". You'll thank yourself later when you need to reinstall. If you're unsure where to find the official offline installer for your specific version of Office, visit Microsoft's support site or your Microsoft Account dashboard—third-party sites are dangerous for this.
If you have a slow, unreliable, or metered internet connection, trying to install Microsoft Office the normal way (via a small "click-to-run" online installer) can be a nightmare. It often fails midway or takes hours. office installer offline
