Tech Tip Guys: Where are my file extensions? |

Tech Tip Guys: Where are my file extensions?

Photo for The Union John Hart

I recently upgraded to Windows 8. Why do files no longer include letters after a period at the end of their names? I used to see file names that ended with .doc and .xls, and even longer names like .docx and .xlsx. What does this information mean, and do I need to do about this? And why do I no longer see this part of the file name?

Back in the "old days," operating systems used a three-letter file extension (like .doc or .xls) to indicate to the operating system an association between the file and the application that you needed to run in order to work with the data file. Every different application that handled data files needed to specify its own distinct three-letter file name extension. For example, Microsoft Word files had a .doc extension, and Excel files had a .xls extension. If two applications attempted to share the same file extension for their data files, confusion was destined to occur. (You can find a possibly too-complete list of standard file extension associations at this site: Operating systems for both PCs and Macs shared this functionality.

As time went on, modern operating systems relied less and less on the file extensions, and the number of letters allowed in the file extensions grew, and it became possible to include more than one period in file names. (For example, a file name like is perfectly legal in current versions of Windows.)

Although Windows and OS X handle file extensions slightly differently, one fact is certain: In a graphical environment, as in any modern operating system, seeing the file extension is far less important than it once was because both Windows Explorer and Finder display an icon indicating the file type next to the file. In each case, you see an icon corresponding to the default application associated with the data file. In both Windows and OS X, you can change the default association so that clicking on a file with a particular file extension runs a specific program, which might be different than the default association. (For example, you could convince Windows to run Wordpad, rather than Microsoft Word, when you click a .doc file.)

Most importantly, you can show or hide file extensions on both PCs and Macs. The steps differ, based on the particular version of the operating system. Search the web for "show file extensions" followed by your operating system (Windows 7, or OS X 10.8, for example), and you'll find the instructions you need.

Finally, you asked why this changed when you installed Windows 8? In your previous operating system had been set to display file extensions, and by default, Windows 8 does not. You can, of course, display them by following the online instructions (both of us are accustomed to seeing file extensions, so always display them in every operating system).

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How can I clean my keyboard?

My keyboard is filthy. I try not to eat at the computer, but you know how it is. And there's all the cat hair. Is there some way to clean the keyboard? And how can I avoid this in the future?

The obvious answer is to get rid of the cats and don't eat at the keyboard.

Ken's a cat lover, and he's well aware that telling you to get rid of a cat to keep your keyboard clean is like asking you to stop breathing. The simple answer is: To clean your keyboard you can use a damp cloth which you just rub on the keys to take off the filth. Really, it works. You probably want to turn your computer off before you do it to avoid typing all sorts of stuff into your current document. And don't get water or any liquid into the workings of your keyboard. Nothing good ever comes from liquids meeting electronic equipment face to face.

Ken, being slightly retentive, has found that using rubbing alcohol (most conveniently, in those sterile alcohol pads that people use before getting a shot) works very nicely too. Beware of rubbing too hard and removing the paint that has the letters marked on your keyboard, and just as when using water, ensure that you don't get alcohol into the workings of your keyboard.

You could, of course, replace your keyboard. This is simple to do if you're using a desktop computer, but it's a little more complicated if you're using a laptop. Note that although your laptop manufacturer might want to charge you an exhorbitant price to replace your laptop keyboard, you can often find third-party keyboards online at or, and they're usually far cheaper than keyboards from the original manufacturer. If you're queasy about opening up your laptop to replace the keyboard, any computer professional can do it for you.

Finally, we recently noticed that Logitech, a company that makes peripherals for computers, has released a washable keyboard. You can dump it in the sink and wash it with a few dishes and it comes out perfectly clean and usable again. All the keys are sealed so it's unlikely to get cat hair inside, and it looks pretty good to us. Ken tried it out at a local store and liked the way it felt. If you're interested in a washable keyboard that works well, try out the Logitech washable keyboard, model K310 (

Doug Behl and Ken Getz spent years answering technical questions in private, and are minimizing the questions by pre-emptively publishing the answers. Hear Doug and Ken's tech tips on KNCO radio weekdays at around 8:21 a.m. and 5:38 p.m.; find full write-ups including links to the products they mention at Submit your own technical questions to

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