While it is technically possible to open an Excel file in Notepad, this is not a good idea. Excel files are binary files that contain complex formatting and data structures. When you open an Excel ...

1] Notepad. Opening an XFDL file in Notepad is a no-brainer. Right-click on the XFDL file, hover to “Open with” in the context menu, and select Notepad.

To open a CSV file in Notepad, you need to open Notepad > click on File > Open. Then, select All Files and choose the CSV file. Read: How to Convert CSV to Excel (XLS or XLSX) using Command line.

To build a CSV file to open in Microsoft Excel, you'll need to decide how many columns you'll use in Microsoft Excel for the categories of information you're preparing in Notepad.