The expression "open a file" has two distinct meanings for programmers and users of software. For a user of Word, for example, "open the file" would mean to be able to see its content in a formatted way inside the editor.

When a programmer - now acting as a regular user - opens a Python file in an editor such as Notepad++ or Pycharm, the expectation is to see the content of that program with nice colors.

However in order to provide this the programmer behind these applications had to do several things.