Learn how to use Microsoft Defender to check your device for viruses or malware on Windows, Android, or Mac. Find out the signs of infection, the types of scans, and how to run Microsoft Defender Offline for a deeper scan.

Learn how to create a USB flash drive or DVD to install or reinstall Windows 11, 10, 8.1, or 7. You'll need a reliable internet connection, a blank storage device, and a product key (if applicable).

Learn how to download and install Microsoft 365 or Office 2019, 2016, or 2013 on your PC or Mac. Find out how to activate Office, troubleshoot issues, and switch languages or bit versions.

Learn how to locate your BitLocker recovery key, a 48-digit number needed to unlock an encrypted drive in Windows. See where to find it attached to your Microsoft account, work or school account, printout, or USB flash drive.

Learn how to download and install or reinstall Microsoft 365 or Office 2021 on a PC or Mac. Find out the system requirements, product keys, activation steps, and troubleshooting tips.

Learn how to connect your Xbox Wireless Controller to a Windows PC using a USB cable, the Xbox Wireless Adapter for Windows, or Bluetooth. Find out how to update your controller, pair with Xbox devices, and troubleshoot common issues.

Learn how to check the recent sign-in activity for your Microsoft account and what to do if you see unusual or suspicious activity. Find out how to change your password, update security settings and contact support.

Find out how to add your Outlook.com account to Outlook or another mail app using POP, IMAP, or SMTP settings. Learn how to enable POP or IMAP access, troubleshoot connection errors, and get help from Outlook.com Community.

如果这是你第一次安装 Microsoft 365，则可能需要先执行一些设置步骤。展开下面的 “了解详细信息”部分。 但是如果是重新安装 Microsoft 365，且已兑换了产品密钥并拥有与 Microsoft 365 相关联的帐户，请转到“登录并安装 Office”的部分。

准备好安装了吗？ 在开始之前，请确保电脑或 Mac 满足 系统要求。. 如果已兑换产品密钥，只需重新安装应用，或者知道你已通过工作或学校分配了许可证，则可以跳到 “登录”部分，下载并安装 Microsoft 365 或 Office。 但是，如果是 首次 安装 Microsoft 365 或 Office，可能需要先执行一些步骤。