A filename extension is a suffix to a filename. There’s the name of the file itself, then a period, then the extension. When you see Document.pdf, the ".pdf" is the extension. The filename extension is one of those things that’s a necessary evil in computing to differentiate one type of file from another.

Some UNIX/Linux environments purposely use specific extensions for the sake of convenience because they’re technically not required. For example, the Debian distribution uses files that end with .deb to represent a Debian software package. When you see a file that ends with .deb, you instantly know what it is. You can consider filename extension use in a UNIX/Linux environment to be more of a descriptor (i.e. metadata) than anything else.

The Windows environment requires filename extensions to operate. Traditional extensions do not exceed three characters. For those of you thinking, "Isn’t is true all file types in Windows use three-character filename extensions?" Not necessarily. 7-Zip for example uses the two-character .7z by default, and several programming languages use one or two-character extensions.

Common filename extensions that confuse people as to what they are

Some extensions are really easy to figure out because they’re part of a word.

Examples: TXT (TeXT), DOC (DOCument), BAT (BATch script file), COM (COMmand), WAV (WAVe sound file), SH (SHell)

Then there are those that are abbreviations, like PDF (Portable Document Format).

But then there are those that do nothing but confuse people because they don’t know what they are. Here’s a few should you encounter them:

M3U and PLS

These are both file types that represent a multimedia playlist. Many get confused when they encounter these because they think there’s actual audio within them. Not true. They are small "pointers" to other audio files (such as MP3) either local to your computer and/or on the internet.

The super-long title for M3U is "Moving Picture Experts Group Audio Layer 3 Uniform Resource Locator". Try and say that 5 times fast.

PLS to the best of my knowledge means either PLaylistS or PLay Stream, although I could be mistaken (and if I am, feel free to correct me by posting a comment).

ODT

This is a file type that that is slowly becoming recognized in mainstream use, that being the OpenDocument Format. The T is for text. There is also ODS with S for spreadsheet, ODP with P for presentation, ODG with G for graphics and ODF with F for formulae (mathematical equations).

Most people know ODT files from using the freely available OpenOffice suite. The ODT format by the way is compatible with Google Docs if you don’t have software to read them.

RAR

Most people know what this is but there are still a few that don’t. It’s a Roshal ARchive. This is an archive format like ZIP. If you want to open one, use 7-Zip or WinZIP (paid software). If you want to create one, use WinRAR (also paid software).

FLV

FLash Video. If you want to view an FLV video independently (meaning not in your web browser), use the freely available VLC.

FLAC

Free Lossless Audio Codec; an audio file type that sounds better than MP3 because it is lossless while MP3 isn’t. To play them you can use Windows Media Player or the freely available WinAMP.

3GP and 3G2

Both of these are usually video file formats and part of the 3GPP standard. You will usually only encounter these when someone sends you a video file via a cell phone. Windows Vista and 7 will view these via Windows Media Player. If using XP, use Apple QuickTime.

M4A and MP4

Both are MPEG-4 Part 14.

Both file types can be either audio or video. While it’s true that most files ending in .m4a are audio-only, it doesn’t mean they have to be.

Windows Media Player 12 – which is bundled with Windows 7 – will play this format. For older versions of Windows you can use Apple QuickTime or the freely available VLC.

OGG

A newer multimedia file format. It can be audio or video. This format can be opened and played on many different programs, including the freely available VLC.

Older file types you may encounter

What’s listed below isn’t in mainstream use any longer, but should you encounter them you’ll at least know what they are and how to deal with them.

ARJ

An archive file type like ZIP and RAR.

ARJ is Archived by Robert Jung. This file type was actually quite popular during the 1990s and at one point gave ZIP some really good competition. 7-Zip is able to open these.

WPS

This is a proprietary document format used by the Microsoft Works when you save a document with it. It is the file extension everybody hates because nobody can open them that doesn’t have Works.

Fortunately you can do a Save as in Works and save in DOC format, but most people who use Works do not do that. And if you use Works, I strongly urge that you always save in DOC and not WPS – especially if you’re sending documents to other people.

Got a bunch of WPSes and need to convert them? Use Zamzar to do it. (WPS conversion, thankfully, is supported.)

TIF or TIFF

This is an image file type. It stands for Tagged Image File Format. Most image editors can easily open TIFF files, including the Windows Picture and Fax Viewer which is included with the Windows OS.

If for whatever reason you have a problem (which you shouldn’t) opening a TIFF, use the freely available GIMP software.

RTF

This is Rich Text Format, a document type developed by Microsoft way back in 1987. It is still, even in Windows 7, used as the default file type when saving from it’s bundled word processing application WordPad.

For older generation computer users, RTF sticks out like a sore thumb due to the fact so many people used Windows Write (the predecessor to WordPad). But many newer generation users have never seen RTF files.

Shades of the past: Using the Start/Run dialog in Windows 7, if you type write and click OK, WordPad will load up.

For those wondering, I am running the 32-bit edition of Windows 7. I did this primarily for application compatibility above all else.

The first response from those who are familiar with 64-bit environments are quick to say, "But you can run 32-bit apps in a 64-bit environment easily."

That’s not always the case.

Running certain 32-bit apps in 64-bit environments can present itself to be a problem no matter what OS you use. For example, many Mac people use Photoshop. All new Macs are 64-bit. But Adobe does not have a 64-bit edition for the Mac. Photoshop still runs fine but doesn’t take full advantage of the 64-bit environment. It also ticked off Mac users something fierce that Photoshop 64-bit will be for Windows first. And if I were a Mac user that would perturb me quite a bit as well.

Per conversations I’ve had with a few folks running Windows Vista or 7 64-bit, two particular types of platforms have exhibited some quirks, also both from Adobe.

The first one is Adobe AIR. It would appear AIR doesn’t "play nice" in 64-bit world except for Linux currently. But on Windows 64-bit, AIR is something which may or may not work. So if you wanted to run AIR apps like Twhirl or TweetDeck on Vista 64 or Win 7 64, it might not even be possible presently.

Did you get Adobe AIR running on Windows Vista or 7 64-bit along with your favorite AIR apps? Let us know in the comments.

The second is a biggie, Adobe Flash. Some I’ve conversed with say Flash runs fine on 64-bit while others say it’s "tolerable" at best.

Did you get Adobe Flash running on your 64-bit Windows Vista or 7? Let us know in the comments on this one too as many would love to hear your experience.

Most people could live without AIR, but as for Flash, there are tons of web sites that simply require it. And going without Flash would be trying on the nerves to many.

I discovered this on a goof. On my laptop I had installed the latest version of WinAMP to listen to MP3s and so on and it had associated itself with FLV extensions (I just did a standard install that auto-associates instead of a custom which it why it happened).

I downloaded a few FLVs as backups from my YouTube channel and double-clicked one to view it – and whammo, up pops WinAMP and plays the video.

Said honestly, yes, this is the best FLV player I’ve used. I was previously using FLV Player to view these files but now I can just use WinAMP instead. It does the job far better than using another app and full-screen works perfect.

If you’re stuck on which to use for a quick’n'easy FLV player, use WinAMP. Works great.

Since the release of Mozilla Firefox 3 there have been issues with the Adobe Flash player (currently at release 9), particularly with Flash video. What happens is that you’ll attempt to watch a video (say on YouTube) and the first 2 seconds will play and then stop. And you’re left with no choice but to restart the browser and sometimes that doesn’t even work.

There is a Flash 10 beta available right now if you want to use it. It’s recently been updated for both Windows and Mac. Personally speaking I won’t be using it because all I have to do is that if Flash bugs up on me I just go into Internet Explorer 7 and everything is okey-dokey. I figure if I want to view a Flash video that bad, going to another browser just for that video doesn’t bother me.

So if you’re a Firefox user and have been experiencing that maddening 2-second-and-stop issue, it’s not your fault. When version 10 of the Adobe Player is officially released it should resolve that issue.

There are a few keyboard and mouse shortcuts in Windows Media Player 11 that are handy to know just in case you ever need to use them.

Switching between skinned and non-skinned mode

Non-skinned: CTRL+1

Skinned: CTRL+2

If you have a kid that sometimes "messes with" the media player and it has this weird skin on it (such as the way it looks at the top of this article), CTRL+1 will fix that in short order so it goes back to "full mode", like this:

Getting the menus to show up on the top bar

The keystroke for this is CTRL+M. To hide them, press CTRL+M again.

Going to compact mode

To make Media Player look like this…

…hit the bottom right arrow (the one at the extreme bottom right). Hit it again to bring Media Player back to full mode.

The list pane disappears, how do you bring it back?

If your Media Player looks like this:

You can bring back the list pane on the right by clicking the small down arrow under Now Playing (top left) and clicking Show List Pane.

Like this:

…and then your Media Player will get the list pane back.

Showing the enhancements

If you want your media player to have extra options like this:

…click the down arrow under Now Playing, then Enhancements, then Show Enhancements, like this:

Alternatively you can directly pick what enhancement you want to view from here also (like Color Chooser or Graphic Equalizer).

Removing this panel can be done by clicking the small X at the top right of that pane, or by clicking Now Playing then Enhancements then Show Enhancements again to hide it.