Find your product key to activate Windows. A product key is a 25-character code that's used to activate Windows and helps verify that Windows hasn't been used on more PCs than the Microsoft Software License Terms allow.

Contact Support For help with your Microsoft account and subscriptions, visit Account & Billing Help. For technical support, go to Contact Microsoft Support, enter your problem and select Get Help.If you still need help, select Contact Support to be routed to the best support option. Admins

When you get a new device and start up Windows 10 for the first time, the antivirus protection that comes installed with the device is your default security app.

Note: If your data is in an Excel table, the Transpose feature isn't available.You can convert the table to a range first, or you can use the TRANSPOSE function to rotate the rows and columns.

Contact Microsoft Support. Find solutions to common problems, or get help from a support agent.

隐私：默认情况下，组创建为“专用”。这意味着只有组织中获批的成员可以查看组中的内容。 组织中未获批的任何人均无法查看组中的内容。 若要创建你组织中的任何人均可查看其内容并成为其成员的组，请选择“公用”。

Internet Explorer 11 support ended on June 15, 2022. If any site you visit needs Internet Explorer 11, you can open it with Internet Explorer mode in Microsoft Edge.

Most software that you buy directly from Microsoft, like Office, Windows, and Xbox games, comes as a digital download that you can download, install, or reinstall.

Use the XLOOKUP function when you need to find things in a table or a range by row. For example, look up the price of an automotive part by the part number, or find an employee name based on their employee ID. With XLOOKUP, you can look in one column for a search term, and return a result from the same row in another column, regardless of which side the return column is on.

An upgrade moves your PC from a previous version of Windows—such as Windows 7 or Windows 8.1—to Windows 10. An upgrade can take place on your existing device, though Microsoft recommends using Windows 10 on a new PC to take advantage of the latest features and security improvements.