What do most file extensions in operating systems mean?

The file extension (filename extension), also known as the file suffix, is a mechanism used by the operating system to mark file types.Normally, an extension follows the main file name, separated by a delimiter. The extension can be thought of as metadata for a type.

Filename Extension (or extended file name, suffix name) is a mechanism used by early operating systems (such as VMS/CP/M/DOS, etc.) to mark file formats. In DOS terms, a file extension follows the file's main name, separated by a delimiter. In a file name like "example.txt", example is the file main name, txt is the file extension, indicating that the file is a plain text file, and the period "." is the separator between the file main name and the file extension.

DOS operating systems (including Windows 3.x) limit file extensions to 3 characters. Personal computers (PCs) have been on other Windows operating systems since Microsoft launched Windows 95, whether it is 16/32-bit Windows 95, Windows 98, Windows ME or 32-bit Windows NT, Windows 2000, Windows XP, Windows 2003 and Windows The FAT32 file system of Vista and Windows 7 contains an interface-level correction so that the number of characters in the file extension can reach 256 English characters (long file name), but at the system level, the 3-letter naming method is still retained. Invisible to many users. The NTFS file system does not have this limitation.

Common file extensions:

##Practical application Instructions Open\Edit mode Chinese and foreign language full name Design Explorer 99 SE opens the ##doc Word document ##txt Notepad, web browser and most other software. TeXT wps xls ppt Open in a web browser or web editor (such as W3C Amaya, FrontPage, etc.) HyperText Markup Language Open with a pdf reader (such as Acrobat ), use pdf editor to edit Portable Document Format Open software such as AutoCAD DraWinG Windows operating system EXEcutable Open with various graphics browsing software and graphics editors Joint Photographic Expert Group Open with various graphics Browse software, graphics editor Portable Network Graphics Open with various graphics browsing software and graphics editors BitMaP ##swf Adobe FLASHVideo

ddb	Protel circuit schematic file
	Microsoft word and other software open the	DOCument
text document ( Plain text file)
##Wps Text Editing System Documentation	Jinshan The company's wps software opens WordProcessingSystem
Excel spreadsheet	Microsoft excel software opens
Powerpoint presentation	Open with Microsoft powerpoint and other software
rar	WinRAR Compressed file	WinRAR, etc. open
##htm or html	Network page file (an application html under standard universal markup language)
pdf	Portable Document Format
dwg	CAD graphics file, (Extended Full name in Chinese: Figure)
exe	Executable files, executable applications
jpg	Common graphics files (Joint Photographic Expert Group)
png	Portable network graphics, a transparent picture
bmp	Bitmap file
		Adobe FLASH Player or various audio and video playback software	ShockWave Flash
fla	swf source file	Adobe FLASH open

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