On the storage devices of your computer, application (program) files and data files are stored. They are organized in folders. Different storage devices have different names, like A: for the floppy disk drive, C: for the hard disk drive, and maybe Z: for the CD drive. Sometimes the hard disk is partitioned into several parts, named maybe C:, D: and E:. Now the hard disk C: contains several folders. These folders may contain files or subfolders, and so on. Only folders can contain files and folders, files contain just the data or programs.
This hierarchy of folders and subfolders and files can be visualized as a tree (that grows downwards).
The path address of each item can be found be going to the item---starting at the "root" "MyComputer". For instance, the path for the grades file "Grades.xls" would be D:\My Documents\Teaching\105\Grades.xls". The parts are separated by backslashes "\".
Wheras the (absolute) path describes the location of the file on the computer, the relative path tells us the path between the location we are presently, and the location of the file. ".." means: Go to the superfolder containing the present file or folder. So, from the SyllabusCPT.doc file, the relative path describing the location of the file "bestfilms.txt" would be "..\..\..\bestfilms.txt", meaning "go to the superfolder, go to the superfolder of this, go again to the superfolder, and finally pick the file "bestfilms.txt" in the folder you ended.
Each file has a name: A word plus an extension, separated by a dot from the word. The extension tells you and the computer what kind of file it is. Applications have usually the extension .exe, but small programs may also have the extension .dll. For data, the extension indicates with what application the file was created and should be opened. Folders also have names, but no extensions.
When you doubleclick on a data file, the program starts. When you doubleclick on a data file the program that created the file starts. But can you view a Word file or an Excel file with Notepad, for instance? Do it and comment.
How would you change the setting which program to use to open a file with a given extension in Windows?