Article in English: Unlike most file types, DAT files can be created by virtually any program; as such, you'll need to know which program created the DAT file to figure out which program to use to open it. If you don't know which program was used to create the DAT file, you'll need to figure out which program to use before you can open the DAT file. Click or double-click the app icon of the program that was used to create the DAT file. This is usually in the top-left corner of the program's window. A menu will appear. It's in the File menu. Doing so will usually open a File Explorer window. If you're using Microsoft Office, you must double-click This PC in the middle of the page after clicking Open to open the File Explorer window. Click the file type box to the right of the "Name" text field, then click All Files in the resulting drop-down menu. This will allow the File Explorer to display all files, including your DAT file. Go to your DAT file's location, then click once the DAT file to select it. It's in the bottom-right corner of the window. Doing so prompts the DAT file to begin opening in your program. In some cases, you'll receive a warning that the file's contents don't match its file extension (or similar). If so, click Yes or Open to prompt the DAT file to open. For example, opening an Excel-created DAT file in Excel may result in a prompt warning you that the file may be corrupted. You can click Yes to open the file anyway. If you want to avoid having to drag the DAT file into its program every time you want to open it, you can change the file's extension. Keep in mind that you must know the exact extension used for the DAT file, as changing the extension to use even a slightly different format (e.g., MP4 instead of AVI) can result in the file breaking:  Right-click the DAT file, then click Rename. Select the dat portion of the file's name. Replace the dat section with the file's extension.

Summary in Vietnamese:
Xác định chương trình đã tạo ra tập tin DAT. Mở chương trình. Nhấp vào File (Tập tin). Nhấp vào Open… (Mở) nằm trong trình đơn File. Hiển thị tất cả tập tin trong File Explorer. Chọn tập tin DAT. Nhấp vào Open ở góc dưới bên phải cửa sổ. Xác nhận rằng bạn muốn xem tập tin khi được hỏi. Thay đổi phần mở rộng của tập tin DAT nếu cần thiết.