Well it’s not the same as a house extension!
Every different type of file has a three or four letter …extension…at the end of it’s name. When you see it in File Explorer it won’t be displayed by default, but you can view it by reading further.
In the example above …docx…is the extension. It’s one you probably recognise as it’s the newer standard extension for a Word document. Some more common ones you might see are .PDF (an Adobe reader or similar file), .XLSX (Excel file), .EXE (an executable file or program).
By default the EXTENSION is hidden in Windows 10, just out of neatness, but the file’s ICON is always the icon of the program or app that will open it. Every type of file has a program associated with it. Sometimes it’s not the one you want…but more of that later.
If you want to see the extension, you could enable them in folder options (as shown here) or a quicker way for an individual file is to view it’s properties. RIGHT CLICK the file and select PROPERTIES right at the bottom:
…and there under type of file you will see the extension in a set of brackets.
SOLVED: What is a file extension in Windows 10?
Read on to learn more….or leave
Sometimes when you install a program (or sometimes accidentally) the wrong program tries to open your file when you double click it. In other words the extension is associated with the wrong program. This is easy to fix, but you have to know both the extension of the file and what program you want to open it with. Go here to see how to do it.
Its good to learn some common types of extension in case things do go wrong. One file type like a bitmap picture (ie. a picture made out of little dots or pixels) can be saved in lots of different formats, but then one program like Paint or Photo Viewer could open them all. So as you can see it can get confusing. Here’s a few to see:
bmp, tiff, jpg, jpeg, png…..these are all bitmap pictures
pdf, doc, docx, odf… these are all types of documents
mpg, mpeg, mov, mp4, avi, wmv….these are all video formats
wav, mp3, flac, wma, aac…are all audio formats
How do I find the file extension of a file in Windows
Why does the wrong program open in Windows
Where is the extension in a file
What do the letters at the end of a file mean