File formats and extensions

When you save a file to a computer, online or in front of you, the file is stored using a file format. A file format is a way of putting the information that you see or hear into a digital scheme on a hard drive. There are MANY different file formats and each has a file extension. For example, if you save a file using Microsoft Word, the format used will likely have the extension docx. This is the extension for the "Office Open XML Links to an external site. document" format.

Here are some tutorials to help you better understand file formats:

  1. Some common file types defined Links to an external site.
  2. File Formats explained Links to an external site.. This is a lengthy article, at least read the first couple of paragraphs.
  3. File extensions explained Links to an external site.
  4. A thorough list of file formats Links to an external site. 
Did you know that just changing the file extension does not reformat the file as the new file type?

For example, I use Open Office Writer as the word processor on my Mac. When I save a file, it uses the odt file extension for the "OpenDocument Links to an external site. text document" format. If I go to my file manager and rename the file autobiography.odt as autobiography.docx, then I haven't actually reformatted the file as the MS Word file type. I now have a file name with a misleading file extension. This will cause some problems when trying to open the file. If I need the file to be in the docx file format then I have to use a program like OpenOffice Writer or MS Word or Google Docs to reformat the file. This is done by using the save as command. Simply open the file using the appropriate program, then select save as. This allows you to specify the file name, the file extension (i.e. the file format), and the file location. In Google apps, we use the Download as command to reformat a file.