With text files (documents) weface almost daily. However, in this question we should not confuse the extension of the text file and the text data format, these are different things. Let's try to decide what files of this type are, and how they are.
To begin with, as a rule, mostfiles of this type have an extension in the form of three letters after the delimiter (dot). The simplest and most common type is files with the .txt extension, opened on the same Windows systems using the standard Notepad.
However, despite the generally accepted rulesText document file extensions can contain not three letters, but more (their number can reach twelve, but not more), for example, .djvu files of electronic books. In addition, the expansion may contain numbers.
What gives us consideration of classificationtext file (document) in terms of their identification? And the fact that one glance allows you to instantly solve an important question: what kind of extension text files have, so is the program associated with it for opening or editing. Here in many cases it is almost always possible to determine the original application in which such a file was created.
But do not forget that today you canto meet a sufficiently large number of files with the same extensions, but created in other applications or associated with different programs. It would seem that a regular file with the .doc extension (.docx) initially corresponds to the text editor Microsoft Word. But after all, it can be opened or saved in this form in another word processor, even on Apple computers. This can also be attributed, and so to speak, a mixed type - files of the .pdf format, containing not only text, but also graphics. But after all, Word documents may contain inserted images.
This is what serves as an indicator thatthe text file extension indicates the universality of the format itself, which is the most “readable” regardless of even the operating system used. The same goes for text editors of any type.
In general, today we know such a huge number of text formats and their extensions that, probably, almost no specialist will undertake to calculate their total number.
Yes, of course, the universality of such documents is notcauses doubts, especially if they use the simplest encoding ASCII. But sometimes the problem may lie in the fact that not every encoding is supported by a particular system or program. That is why instead of the usual letters a set of characters appears on the screen.
As for the varieties of text files,you can't list them all. The most common are the following: .txt, .doc, .tex, .text, .pdf, .log, .apt, .ttf, .err, .sub, .djvu, .odt, .rtf, and many others. This list is endless.
What is most interesting, many files of this type inthe system has a different role. For example, besides the usual subtitle file .sub, a regular text document .txt can be responsible for viewing them when opening a video, and in this respect many formats are interchangeable.
Notice, even executable files may havetext as content. The simplest example is a .bat file created in a regular Notepad and containing text as a set of commands. At startup, the commands are executed, and the “Open with ...” menu is used for editing if there is no other action associated with this process initially.
A similar situation is observed with documentsusing markup or programming languages, such as .html, .htm, .xml, etc. Even web pages can be opened in many editors initially as text files containing third-party elements.
As for changing the extension, sometimes itYou can change, for example, .txt in .doc and back. Word editor will open any type. The same applies to the pair .txt - .bat when opened in Notepad. But in other cases it is better not to perform such manipulations, it simply will lead nowhere, and another application cannot open the renamed file. The format change will have to be made using special converter software.
Как уже понятно, расширение текстового файла may have many variations, depending on which program the document was created in. But, as well as in other cases, by the extension itself, it is almost always possible to determine the associated application initially to it, at least open it with any other program supporting work with this type of data, even if the original application is not on the computer. And as is probably understandable, it is text files that, in fact, are the most common and universal in the computer world, regardless of the software packages and operating systems used.
