A File Extension is the end name of the file which helps you to identify the file type in Operating System such as Windows. The File Extension is followed by two to four characters.
Below are different types of file extension:
Doc/Docx: The extension is used for the word document.
Xls.Xlsx: This Extension is used for Excel Spreadsheet
PNG: Portable Network Graphics for image file
Html: Hyper Text Markup Language used for creating online web pages
pdf: Portable Document Format used to maintain formatting in distributed documents
exe: An Executable format used for programs you can run.
Show File Extension in Windows 10
Open Control Panel-> Appearance and Personalization.
Click on File Explorer option
In VIEW. Uncheck the option of "Hide Extension for know file types"
Click on Apply.
Below is the images where you can easily see the difference. First image is when you uncheck "Hide Extension for known File types".
And Second image is When you check "Hide Extension for known file types." You will not see any file extension. See the image below:
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