Unknown? Pleased to meet you!

Question: After a file is downloaded, how do I open it when it asks me to “open with?” and it gives me this big long list to choose from. What am I supposed to do then? –Bill E.

Answer: Windows figures out what program to use to open a file by looking at the file name. In the old days, a file name looked like this: filename.abc. Where filename was an eight-character name with no spaces, and . abc is a three-letter extension. It could be any one of hundreds of three letter combinations.

Some common ones include txt (for a text file), jpg (a compressed image), doc (a Microsoft Word document), or ppt (a Microsoft PowerPoint presentation).

That changed with Windows 95. Now a file name can be any number of letters numbers and some punctuation and can include spaces, but the three letter extension is still required. So a file today can look like this:
grandma wearing a funny hat being goofy.jpg.

Windows figures out which programs to use to open any given file by keeping a hidden index of file extensions and their corresponding programs. When you install new programs, they tell Windows which file types they can open.

If a program is not assigned to a particular file extension, then that is put in the index. If a program is already assigned to a particular extension, you are prompted by the program during the installation as to whether or not you want to assign it to open that file type. If you say “yes,” that program is assigned in the Windows index as the program to open that kind of file.

If Windows does not recognize a file type, and no program has been assigned to open it, Windows will offer you a list of program that might be able to work with it. You have to make a decision as to which program to use to attempt to open it. That’s what Bill E. is asking about in the question that started this column.

The best way to manage this process is to save the file after downloading it to a place on your hard drive that you can find later. I always create a folder called Downloads on my desktop and save all the files I get from the Internet into that folder.

Once you have finished the download and saved the whole file to your computer’s hard drive, go and find it. Click on it once, but don’t open it. Right-click on it and select Properties from the menu that appears.

A box with lots of information will open. If you’re using Windows XP, look for the Type of File reference. This will tell you what program is assigned to open it. There is also a Change button. If you click this, you can reassign the program used to open it.

If you are using Windows 95/98 or ME, the process is not as straightforward. Look for the Type reference. This will tell you what program it is assigned to. Then look at the MS-DOS name, and you should see the name of the file including the three letter file extension.

If you see something like GRANDMA~.JPG, note that this is the truncated name assigned to it by MS-DOS. MS-DOS is the Microsoft operating system that came before Windows. It can only use eight characters in the first part of the name. The squiggle means that the file name was created with a longer name in Windows 95 or later.

If it’s not immediately obvious what program can be used to open the file, you can look up the three letter extension, either using the web (try filext.com) or using a program called “File Investigator” at http://www.robware.com/.

If you don’t have the program that will open the file, you need to go and get it and install it. Here are some programs you can use to open common file formats.

A good free image viewer for JPG, GIF, TIF, PCX and BMP files is Irfanview, available for free to download from http:www.irfanview.com.

If you want to open a TXT or RTF document file, use Windows Notepad or Wordpad. Both can be found by clicking Start, then Programs, then Accessories.

PDF files can be opened by Adobe Acrobat Reader. A free viewer is at www.adobe.com.

If your file is an EXE file, you can simply double-click it. Windows doesn’t open it like a file with another program; it will automatically run it because an EXE file is an executable program.

A ZIP file is a compressed archived file. Windows 95/98/ME users need to use WinZip to unpack it from www.WinZip.com. Windows XP automatically opens these files like a folder and then you can take the files in the ZIP file and move them out of the ZIP folder and treat them like normal files.

Note that DOC files are Microsoft Word document files and require Microsoft Word or WordPerfect to open them.