I'm a slave for file extensions

Posted on January 21, 2002

A reader once questioned me about extensions. Perturbed,

I responded, "Maybe they work for Britney, but I'm not

ready for hair extensions." Then I fell out of my chair,

hit my head on the keyboard and realized he meant file


Anyone who has used a computer has probably seen a file extension. A filename usually contains three parts: a name, a dot and an extension. Some of the programs you use daily automatically add extensions when you save your work. For instance, if you see a Microsoft Word document, it may have a .doc extension. A Microsoft Excel file has a .xls extension, and a text file has a .txt extension.

Actually, the reader was more concerned about extensions on Web files. That barely saved me from purchasing bright pink extensions from an unnamed Web site, but I couldn't resist. Three extensions in which you may see are .htm, .asp and .pdf. There are many, many others, but I'm still missing some letters after knocking my keyboard to the floor, so I'll just explain these.

The first one, .htm, or .html, is the most common. This stands for Hypertext Markup Language, the original Web language. There really isn't much difference between the two, other than the 'l.' It looks as if the truncation came about due to an older Windows platform only allowing three-letter extensions, but I don't even think Britney knows for sure about that one. If you were to open the source code on a page (which can usually be accomplished under the View menu at the top of your browser, under the choice "View Source" or "Page Source"), most information you see will be coded in HTML format.

The next type, .asp, stands for Active Server Pages. Basically these are pages that have the ability to interact with a database in order to show information based on your search or even a pre-defined search. If you were to view the source code on this type of page, you most likely wouldn't see any ASP code, because it's hidden from the end user.

That's a lot of technical stuff. I recommend you take a short break and play Britney vs. Christina in Soccer.

Well I hope you won. Back to extensions. The third extension I decided to explain is .pdf. PDF stands for Portable Document Format. PDFs can hold a large amount of data and can be viewed in Internet Explorer or Netscape, a Mac or PC, and look exactly the same. Depending on whether or not you have the Adobe Acrobat plugin for your browser, you may have to download software to view these files.

There are plenty of other extensions. Two that come to mind are .cgi and .php, which are both similar to .asp in that they allow executable functions, database calls, etc. Occasionally I run across file extensions I don't know, but I can usually find documentation, oftentimes under my broken keyboard, that tells me what they mean. If you are having trouble with a certain file or file extension, send me the name and I'll do the research for you.

Or do what I do and just search for it in Google, the unofficial sponsor of this column. Maybe I can get Britney to share her Pepsi sponsorship so I can write more columns. Then again, I would probably have to give up the pink hair extensions. Oops, I did it again, I dropped my hair under the keyboard.