By the command Options of the Explorer, we associate a program to an extension. So, when you click on a file-picture of extension .bmp, you see it in the associated program. It is also possible to define a secondary editor, launched by rge context menu, that appears by a right clicking on the file.
Alas, the access to these associations is made by what Windows call the file "type", which is an explanation of the extension. So, for the extension ".avi", the type is "Videao Clip", and it is not easy to guess what it is, when you see more than one hundred types... It is badly exciting...
To find quickly the association of an extension
Associate corrects this default. You make your associations from the extensions, and the type is only an explanation.
To download this software created by Wilbert Hengst in Dutschland, go to his page.