Computer file extensions

Did you know that when you save a file the computer automatically adds a period and three letters to the end of the name you give the file.  In the old days, before the Windows operating system, file names used to look like this:
file extensions
Technically speaking, file extensions like:  .exe, .bmp, and .log are still being used by your computer.  However they might not always be displayed with the file name.  They are still important because they tell the computer what program to use to open a file.  Below are some common Microsoft file extensions that you might see and the programs that opens them. Notice that the newer versions of the programs all hav an "x" added to the file extension to differentiate them from the older files.
ExtensionProgram that opens it
.docMicrosoft Word 2003 or older
.docxMicrosoft Word 2010 or newer
.xlsMicrosoft Excel 2003 or older
.xlsxMicrosoft Excel 2010 or newer
.pubMicrosoft Publisher 2003 or older
.pubxMicrosoft Publisher 2010 or newer
.pptMicrosoft PowerPoint 2003 or older
.pptxMicrosoft PowerPoint 2010 or newer
Some file extensions, especially the ones used on the internet, tell you what kind of file something is.  Here are some examples:
ExtensionWhat it probably is
.htmA web page
.gifA graphic or animation
.jpgA photograph or image
.pngA photograph or image
.mpgA movie or animation
.pdfA portable document file (Adobe)
.mp3A sound or music file
.mp4A movie or animation
If you'd like to see even more file extensions here's a website that claims to list "every file extension in the world,289933,sid9,00.html

PRACTICE ACTIVITY:  Look for a file extension in a file name when you're working at your computer today.

TO KEEP ON LEARNING:  To learn more about file extensions try searching the internet for:
File Extensions
Common File Extensions