You can open .DAT files that contain text, with text editors, like Notepad, Notepad++, VS Code, etc. But it is not possible to know what contains in a DAT file.

Though DAT files, which house data as the shortened name implies, are usually best left alone, here's how you can open them.

Learn how to use a Microsoft 365 setting to choose whether to open files in the online or desktop app, giving you full control for each file.

How to launch a specific Microsoft 365 file at startup Windows can also open a file at startup, if you put a shortcut link to it in the Windows startup folder. To create the shortcut, do the ...