Hello, dear guests.

You don't know what a file extension is? Are you confusing it with the format? So, I wrote this article for you. Here you can read about why extensions are needed, what they look like, and see a list of the most popular ones.

Explanations

Straight to the point: an extension is a combination of characters that is written after the dot in the file name. It indicates its format, but is not itself a format.

Writing Features

Most extensions consist of three characters, because for a long time there was such a size limit in the CP/M and . But now the limit has been lifted. It also happens that one combination follows immediately after another, for example, “.tar.gz”.

By the way, in file systems FAT16 file name and extension existed separately from each other. I mean that the dot was not part of the full file name, but simply separated it from the extension for visual convenience.

In the FAT32 and NTFS file systems, dots are allowed to be used in names, so they can appear in any place and number.

Purpose of extensions

The extension is necessary so that the user and operating system understood what a particular file contained and through which program it should be opened.

For example, the name blog.docx indicates that we have a document in front of us and it can be launched using Microsoft Office Word.

By the way, the operating system by default provides programs for opening files of different formats. This is, for example, an “Image and Fax Viewer” for photographs and pictures, etc. The software settings contain a list of extensions, because the same program can open several of them. For example, in the player Windows Media you can listen to music and watch films in different formats.

Therefore, be careful when renaming files. They may not open if you change the extension. True, this does not apply to adjacent formats. For example, if you change .txt to .doc, Word will still understand what you are talking about and will open the file.

File name without extension?

If you do not see the extension in the file name, then its display is disabled in the system settings. To fix this, open the Control Panel through the Start menu, select the “Folder Options” section in it, and in the new window on the “View” tab, scroll down the list of “advanced options” and uncheck the function that hides treasured characters.

List of popular extensions

As you understand, on this moment there are countless programs designed for the same number of extensions. So, of course, I won’t list all of them. I will name only the most common:

Extension	File type	Opening program
.doc or .docx	Document	MS Word
.xls/.xlsx	Table	MS Excel
.txt	Text file	Notebook
.ppt/.pptx	Presentation	MS PowerPoint
.mp3, .flac, .ogg, .waw, .ape, .m4a, .ac3, .wma, .aac, etc.	Music files	Various audio players with corresponding codecs
.jpg / .jpeg, .bmp, .png, .gif, .ico, .tiff, .raw	Images	Corresponding utilities tailored for individual program formats, graphic editors
.avi, .mkv, .wmw, .3gp, .mpeg, .mp4, .flv, .mov, .vob	Video files	Different players with the necessary codecs
.zip, .rar, .7z, .tar, .jar, .gzip, .gz	Archives	WinRar and 7-Zip
.html, .htm, .php	Internet pages	Browsers
.iso, .img, .vcd, .mds /.mdf, .vdf, .nrg, .daa,	Disk images	There are different programs for different files. The most popular: Alcohol, UltraISo, Nero, Daemon Tools, etc.
.pdf	An electronic document into which printed publications are often translated	Adobe Reader and others
.djvu	Compressed image. Scan without data loss	DJVUReader or other programs for reading this format
.dll	Software module	Does not open. When necessary, it is connected as a library using certain Windows components
.ini	Configuration file	Loads settings to the file it refers to
.msi	Software Installer	Actually, the software that needs installation
.swf, .flv	Animation or video on the web	Browsers with Flash Player

There are also files without extensions. As a rule, these are systemic.

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Every day the user works with different files, but does not pay attention or does not know what the file extension is? Or it can be called differently: “file name extension”. Using the file extension, the operating system understands which program can open the file, and to be more precise, when installing a program, data is entered into the registry that indicates the extensions and also the programs that can work with them.

In order to be able to see what extension the files have, you need to enable the function to display file extensions.

Displaying file extensions in Windows

To enable the display of file extensions in Windows XP, go to “Start” - “Control Panel” - “Folder Options”. In the next window, select the “View” tab. Next, uncheck the “Hide extension for registered file types” checkbox below and click “OK.”

For Windows Vista, you need to go to “Start” - “Control Panel” - “Folder Options”. In the next window, select the “View” tab. Next, in “Advanced options”, uncheck “Hide extensions for known file types” and click “OK”.

If you Windows user 7 and don't know how to enable file extensions in Windows 7, then the information below is for you.

“Start” - “Control Panel” - “Folder Options”. In the next window, go to the “View” tab, then below, uncheck the “Hide extensions for registered file types”, click “OK”.

Attention! When the user turns on the function of displaying file extensions, he forgets that if he removes the extension, the file will not be able to be opened. To open the file, you will need to specify the file extension.

Important! Users, please be careful when renaming a file, pay attention to the file extension. For example, if the file name is “Sample Solution.doc,” only “Sample Solution” needs to be changed, and do not delete or change .doc.

To hide file extensions in Windows, you need to check the box “Hide extensions for known file types” and click the “OK” button. For more information on how to remove a file extension, read above.

What is a file extension? The file name extension is the sequence of characters in the file name after the period (for example, "New Text Document.txt") that is intended to identify the file format.

Why do you need to see it in Explorer? For example, in my situation, to create empty sitemap files for a blog from files in .txt format into .xml and .xml.gz formats for their subsequent uploading to hosting.

Default operating Windows system does not display file extensions. And having created a simple text file (or a file of another format), we do not see its extension.

That is, by renaming the “New text document” to “sitemap.xml”, we will see on the screen a file called “sitemap.xml”.

But in reality, when displaying the extension, it will be “sitemap.xml.txt”, which does not suit us at all, because we need exactly “sitemap.xml”.

In order to correctly rename the file and give it the extension we need, we need to make some settings in the Windows Control Panel.

FILE EXTENSION

Click “Start” - “Control Panel”.

In the Control Panel, click on “Appearance and Personalization”.

Click on “Folder Options”

In the window that opens, go to the “View” tab.

We look for the item “Hide extensions for registered file types”, uncheck it and click on the “Apply” and “OK” buttons.

File extensions are a privilege primarily of operating systems with a graphical interface. Their main purpose is to tell the operating system which program should be called to open a specific file.

What is a filename extension?

File name extension, (file type, file format) is a sequence of characters that helps Windows understand what kind of data is contained in a file and which program should open it. This sequence of characters is called an extension because it appears at the end of the file name, following the period. In the file name myfile.txt, the extension is txt. It tells Windows that this is a text file that can be opened by programs associated with that extension, such as WordPad or Notepad.

How can I configure the association of programs with a file name extension?

Each program installed on a computer can open one or more specific types of files, each of which is recognized by its file name extension. If a certain type of file can be opened by several programs installed on the computer, then one of them is installed for use by default. To change the program that automatically opens the file type, see the post

What is the maximum file name length?

Windows typically limits file names to 260 characters. But the actual file name should be shorter, since the full path is included in this number (for example, C:\Program Files\filename.txt). Therefore, sometimes you may encounter an error when copying a file with a very long name to a folder that has a longer path than the current folder.

What characters cannot be used in a file name?

The following characters cannot be used in the file name: \ / ? : * " > < |

How can I see the file name extension?

By default, Windows hides file name extensions to make file names easier to read, but you can make the extensions visible. For more information, see post Show or hide file name extensions.

How to change the file name extension?

In general, you should not change file name extensions because doing so may make it impossible to open or edit the file. However, sometimes changing the file name extension can be useful—for example, when you want to turn a text file (.txt) into an HTML file (.htm) so that you can view it in a web browser. To change the file name extension, first make sure the extensions are displayed. Then click required file right-click and select Rename. Remove the file name extension, type a new extension, and press ENTER. Windows will warn you that if you change the file name extension, the file may not function properly. If you are sure that the program you are using recognizes the extension you entered, click Yes to confirm the change.

Let's not talk about all kinds of extensions pointing to executable files, since the operating system command interpreter is also a kind of program that works with files that have a mask, for example, .COM; .EXE; .BAT; .CMD; .VBS.

Executable file extensions.

Most common file extensions in Windows

Extensions most often found on a computer are usually three-digit sequences of letters and numbers that help the OS start up immediately the desired program to display,

Eg,

Lossless audio files

(lossless compressed audio files) can have a flac, ape or wav extension.

Among the most popular formats for storing images the following are used:

1.JPEG- the most popular storage format raster images(drawings, photographs, etc.). This format involves a high degree of compression of the contained information, which ensures a relatively small size of JPEG files. In this case, compressing photos without losing quality, unfortunately, is not impossible. However, to post photos on the Internet or send them by e-mail, it is advisable to change the photo format to JPEG. This is an economical and convenient format for storing raster information. Supports 16.7 million colors.

2.BMP- standard format graphic files for Windows. As a rule, the BMP format is used for drawings made in the Paint editor, or, for example, standard “wallpapers” for the desktop. Photos in BMP format are stored uncompressed and can take up a lot of disk space. In this regard, it is often necessary to change the photo format to a more ergonomic one (JPEG, TIF, GIF).

3.TIF- raster graphics format that allows you to compress images without loss of quality. Supports 16.7 million colors and is considered a standard format for exchanging data between computers. Popular among professionals, such as digital camera users.

4.GIF- literally translated as “graphics data interchange format”. Files stored in the GIF format are small in size and can consist of several “frames”, which allows you to create simple animations. The main disadvantage of GIF is the limited color range of this format. Therefore, to store multicolor images, it is more advisable to change the photo format to JPEG or TIF.

Vector images

The extension depends on the program in which they are made - for example,

AI (Adobe Illustrator), CDR (Corel Draw), CGM (Computer Graphics Metafile), EPS ( Encapsulated Postscript format),

PS (PostScript), SVG (Scalable Vector Graphics), WMF (Windows Metafile), EMF (Extended Metafile)

Animation

APNG (Animated PNG), Autodesk Animation (.fli/.flc), Animated GIF, Adobe Flash(.swf) etc.

Text documents

text file (.txt), AmigaGuide (.guide), OpenOffice.org/StarOffice Writer (.sxw) (open text format),

TeX (.tex), Texinfo (.info), WordPerfect (.wpd), Microsoft Word(.doc, .docx, .docm) (protected Microsoft format, changes frequently, quasi-standard)

Internet (Web pages)

• Static
  • HTML - (.html, .htm) - HyperText Markup Language
  • XML - (.xml) - eXtensible Markup Language
  • XHTML - (.xhtml, .xht) - eXtensible HyperText Markup Language
  • MHTML - (.mht, .mhtml) - archived HTML (web archive), stores all web page data (text, images, etc.) in one large file, packaged according to the MIME standard (MIME HTML)
• Dynamically generated
  • ASP - (.asp) - active server pages from Microsoft (Active Server Page)
  • ASPX - (.aspx) - active server pages based on .NET from Microsoft (Active Server Page .NET)
  • ADP - AOLserver Dynamic Page
  • BML - (.bml) - Better Markup Language (templating)
  • CFM - (.cfm) - ColdFusion interpreted scripting programming language
  • iHTML - (.ihtml) - Inline HTML
  • JSP - (.jsp) - JavaServer Pages
  • Lasso - (.las, .lasso, .lassoapp)
  • PL - (.pl) - Perl programming language
  • PHP - (.php, .phtml) - abbreviation for PHP: Hypertext Preprocessor, was originally an abbreviation for Personal Home Page
  • SSI - (.shtml, .stm, .shtm) - HTML with Server Side Includes

Table of the most common extensions:

Extension	File type	Example
exe	programs	ACDSee9.exe
com		Command.com
doc	documents (Microsoft Word)	Letter.doc
xls	tables (Microsoft Excel)	Catalog.xls
txt	text documents	text.txt
ppt	presentations (Microsoft PowerPoint)	Presentation.ppt
htm	Internet pages	Book.htm
html		Book.html
hlp	reference	Windows.hlp
bmp	drawing, photography	Figure.bmp
jpg		Photo.jpg
tif		Nature.tif
gif		Figure.gif
mp3	Music	Song.mp3
mpeg	video	Film.mpeg
avi		Clip.avi
zip	ZIP archive	Abstract.zip
rar	WinRAR archive	Abstract.rar

The extension can be long and more than 3 characters in modern Windows, but in Linux its presence is not at all necessary.

In general, file extensions in Windows are often depend on the specific application, and open third party application files with this extension may be difficult or even impossible. So, for example, the psd extension has files created in graphic editor Adobe Photoshop(however, this program allows you to save the finished file in almost any graphic format). Text files created in Microsoft Word can be recognized by the extension doc (docx for new versions of the program), and text editor Open Office works with the odt format. Also text files may have txt or rtf resolution.

How to find out,
What types of files does your operating system work with?

Go to Conductor, in the drop-down menu Service select item Folder properties

and in the dialog box that opens, go to the tab File types.

On this tab there will be a table in two columns - the file extension in Windows and the corresponding one.

!!! Important If your computer is configured to show file extensions, then when you change the file name, leave the extension as is. That is, change the file name to the dot. If you change the extension, the file may no longer open. Remember this!
strana-sovetov.com

What is a file extension?

File extensions- this is some kind of metadata. Typically, a file extension is used to indicate the type of data that can be stored in a file. Thus, a file extension is a sequence of characters that are intended to identify the file format. Usually the extension is separated from the main file name by a dot. In early operating systems, the extension was limited to only three characters, but this limitation was later removed. Some files have several extensions that follow each other (for example, .tar.gz). Operating systems automatically match the extensions of certain files and the programs designed to work with those files. And after such a comparison, the operating system will automatically open a file with a certain extension in the program that was associated with it.

The file extension and its name are separated by a period, for example, index.html, where html is the file extension. Looking at the file extension, you can immediately tell what kind of file it is - text, picture, sound or program. File names may or may not have extensions. Computer users have some conventions about using standard extensions in file names. Programs that create information different types, usually assign standard permissions to the names of the files in which this information is stored. And by the type of this permission, the user can draw a conclusion about which program was used to create the file.

How to find out file type by its expansion?

The following are ways to determine the file type by extension:

Termin.narod.ru- this site contains an extensive list of file extensions; to find the extension you need, you only need to select the letter with which it begins.

Uic.vsu.ru- The most popular extensions are collected here.

Filetypes.ru- this site contains the most complete search database of file extensions; you just need to enter the required extension into the form.

Filext.com- website on English language, where you can also get information about the file extension by entering it in the form.

Another way is the program Know Extension Pro, which determines the file type by its extension. The English database contains more than 23,000 file types, the Russian database - 2235. The program can work from the context menu and in compact mode. You can add your own definitions to the extension database. The program is distributed free of charge. The purpose of the program is to determine its type by the file extension. The program will be useful both for novice users who want to find out the purpose of certain files, and for experienced users who want to create their own knowledge base, since with the help of this program you can add new data to the database.

To start working with the program, simply drag the file of interest into a special field in the program window, or select the menu item File - Open. If such an extension is contained in the database, its description will be immediately displayed.