How does MS Windows know which application to run when a user double clicks on a file?

Question

How does MS Windows know which application to run when a user double clicks on a file? please elaborate.

Answer 1

When an application (say, MS Word) was installed, it writes into the registry which types of files it will open (EX: Office.Word.Document.Type), and within that file type it registers all the different file extensions (EX:. DOC, RTF, DOT, etc.)

When a file of a certain extension is opened, Windows searched back, from extension, back up to the opening program, then launches that program and the file.

Answer 2

All the provided answers are correct, and in case you were wondering how to change the application that opens any given filetype, right click the file, then goto properties, then find the "opens with" section, hit the change button and select your desired application. Hope this helps ;)

Answer 3

Because the file has been associated with the program that opens it! When you install a program, windows associates the files it uses with that program so when you try to open the file it will launch the program for you!

Answer 4

It looks at the file extension, and compares it to a list of programs that can handle that type of file. Usually, windows comes with default choices (like Notepad for .TXT). Programs you install like winamp can override those defaults via manipulating the windows registry.

Answer 5

Windows stores what is called "file association". This tells Windows what to open when a certain file type is clicked on: ex: .doc is Word, .pdf is acrobat reader etc....