File names in Windows have two parts. The first name which we usually refer to it by and an extension after the period in the name. By default Windows only displays the first part of the name for extensions it recognizes.

The extension either tells us what type of file or what program it is associated it with. For instance, files created in Microsoft Word have an extension of doc or docx. The doc was used by Microsoft Office before version 2007 and starting with 2007 changed how the file is stored and the extension to docx (it is now stored in a xml file is reason for x). Text type files normally have an extension of txt

The icon beside the file name will also tell you the program associated with the file extension however most people do not remember most of these icons or pictures.

File names must all be unique within a folder. However, that rule is looking at the full name and they may have same first names but different extensions but the way File Explorer displays the files without extensions you may think it has several files with the same name.

To change the setting so File explorer displays extensions in Windows 10 when using File Explorer (shows folders and is different than Internet Explorer) you will open File explorer. To do that either click the folder on the Tsk Bar are the bottom or the screen or lick Start and the little folder on the left of the menu or right click the start button and choose File Explorer. Then click View tab. Check the box beside file name extensions. Unchecking the box with no longer show the extensions.

To change the setting so File explorer displays extensions in Windows 7 when using File Explorer (shows folders and is different than Internet Explorer) you will open File Explorer. To do that either click the folder on the Task Bar at the bottom of the screen or click Start and Computer. Click the Organize tab and choose Folders and search options. Click View and check Hide extensions for known file types. To hide them check that box.

Thanks to my COMP 1000 students for the question.