Every computer user should know thatin the system there is a huge number of all kinds of files that differ in type. In most cases, they are even graphically marked with different icons. Let's see how the file type is related to its extension and what information can be extracted from it.
What is a file extension?
First of all, it is necessary to clearly realize thatthe file extension did not come from somewhere from the ceiling. The extension of the file name, as a rule, characterizes its type, or rather, it was created by shortening the main description.
As the simplest examples,say, a file with the extension .exe (short for Executable or in Russian "executable" file) or .wma (short for Windows Media Audio - sound type), etc. As you can see, the extension of the file name, as a rule, characterizes not only its type, but also membership in the main program, which is provided in the "operating system" for its discovery. Let's see how this is perceived by the system itself.
File name extension: what characterizes this reduction?
You can not talk about file types without taking into accountapplications that are initially able to open them. However, and here not all so is simple. Look, because EXE files, in fact, themselves are programs and are designed to open other files.
Besides, with the help of executable componentssuch as .exe, you can directly open projects or documents created in this application, unless another program is associated (which is quite common). For example, documents with the extension .doc (native Microsoft Word format) can be opened not only in a standard office application or in WordPad, but also in most third-party programs.
As for some program files,for example, dynamic libraries .dll (short for Dynamic Link Library), the extension of the file name, as a rule, characterizes that although such a component is executable, it does contain executable code that can only be run using system tools such as Rundll32 .
Another example could be universalsounds of banks (.fxb files). In this case, the file name extension is characterized only by the fact that it can be opened in any virtual synthesizer that supports this format. In other words, to work with them there is no single universal program, and any application that can recognize this type can be used.
Recognizing file types
As already mentioned, the file name extension isrule, characterizes not only its type (format), but also belonging to a particular program with a default association. In the case where the association is specified, the file is opened automatically.
Probably everyone noticed that most of the filesin the same "Explorer" are indicated by different icons indicating the present mapping. Opening can be done with a simple double click from the file manager menu or with the help of the corresponding command of the running application. In addition, you can always use the standard Ctrl + O keyboard shortcut, which is an analog of the Open command.
Another thing is when the file is not marked in the systemany icon. Of course, this does not mean that the system does not know what kind of data it is. It is very likely that you can open the file in several ways. That is why in this situation, several variants of programs can be offered, which, by comparing the data in the file itself, select programs that are conditionally able to work with this type.
However, let's return to the fact that the system does notrecognizes a particular type of data. Take a simple example: the .dmg file. In this case, we are dealing with the disk image, but! The extension of the file name, as a rule, characterizes only the moment that it was created not in Windows, but in Mac OS X. Naturally, there is simply no means for opening this type of files in Windows initially. Even if you open a file (if you have certain programs, you can do this), it's still not possible to use the extracted information in the future (yes, it just will not work).
Conclusion
Here in brief and all that can be said aboutfile extensions. Note that this is a very short review, because if we consider the types and file formats themselves, there are so many of them today that it is simply not possible to describe them all individually, including the methods of discovery.
The main thing is to understand that the file extension isthe characteristic of its type (sound, video, graphic, text, etc.). It is formed by the abbreviation of the name, and (in some cases) directly or indirectly indicates a way to open or use some process to work with it.
