File-formats and extensions - file naming conventions


Every file on your computer must have a name, sometimes you gave that name, sometimes the system did. That name is unique, otherwise you yourself and the computer couldn't find anything on the system anymore. So you can't have two different files with the same filename. At least the filename can't occur twice in the same directory, technically you could use the same name in another directory, but it's obvious that this may lead to misunderstandings. So it's a lot easier and safer to give each file a different name.

For a better understanding, it's very useful to have some basic knowledge about how your system works with files.

File-formats and extensions

Every filename consists of the name itself, and a so-called "extension". That's the three (or sometimes more or less) letter-code after the filename. Filename and extension are separated by a point, which belongs to the extension. The computer uses the extensions to know what kind of file it is and what to do with it. This is known as the "file-format".

Example: in the filename "MyLetter.doc", the filename is "MyLetter" and ".doc" is the extension. The file (or the "document") is in the ".doc"-format.

Remark: if in Windows Explorer, those file-extensions don't show up on your computer, this simply means that your configuration is set to hide them (the default setting). To change it to show the extensions (and some other things), in Windows Explorer, go to the Options in the menu "Extra", and on the view-tab uncheck the option to hide file-extensions. You may also want to check/uncheck some other options there, resulting in a much more advanced and wider file viewing. You can do this without risk, for in case you don't want to keep the changes, you always can set them back to default by clicking the standard/default button.

As the filename "MyLetter" literally means nothing to the computer, it's thanks to the extension ".doc", the system will know it's a text-document written in Ms Word and next time you open the file, it will remember to start Ms Word (or another suitable word-processing program). Without the extension, the system won't know what to do with the file.

Another example: if you save a picture on your computer, lets say "mypicture.bmp", then by the extension ".bmp" the computer knows it's a picture and it's to be opened and viewed with an image-viewer program. The file (or "document") is in the ".bmp"-format.

Remark: out of the above follows that you must have a bundle of suitable programs on your computer to open an view the different kinds of files with their different extensions. Most of the time, this won't give much problems, 'cause most programs you need to open and view the most commonly used file-formats are already build-in into your operating system.

But remember, when you've got a file and you can't open it, then probably you don't have the right program to view it installed on your system. If you got that file from someone other, then ask with which program the file was created.

File naming conventions

In the early days file-naming conventions were a lot stricter, a file-name then could only consist of maximum 8 characters, followed by the point and the extension, while a directory (folder) name could consist only out of 11 characters; spaces and some other characters were never admitted.
Example : in the filename "myletter.doc", the name "myletter" could only contain 8 characters, no more.

Since the introduction of windows 9.x those conventions are far more relaxed, and now you can use long file- and folder-names, including spaces (although some characters (such as the slashes, the asterix and other) are still forbidden, but windows will warn you about that). So normally you shouldn't encounter much problems when using long filenames, but... as there're lots of programs on the market, many of them do still have difficulties with some file-names; especially when there are spaces in the file-name...

Repeat ;-) especially when there are spaces in the file-name...! A well-known problem is that a program refuses to open a file from within windows-explorer because the file-name, and/or the folder-name contains a space; remove the space(s) in the file-name and everything goes fine...

So if you want to stay on the safe side, do not use spaces in a file- or folder-name, you can safely use the underscore (_) or hyphen (-) character instead, or you can switch between uppercase and under case characters (see the examples below).

e.g.: use the file-name (without the quotes) "Letter-to-Alice.doc" or "letter_to_alice.doc" or LetterToAlice.doc" instead of "Letter to Alice.doc"




Related topics : Image formats - The "potentially dangerous file" list


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