File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

BIN file extension

Binary Disc Image

Disk Image Files

CLASS file extension

Java Class File

Developer Files

CUE file extension

Cue Sheet File

Disk Image Files

CUR file extension

Windows Cursor

System Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

HTM file extension

Hypertext Markup Language File

Web Files

ISO file extension

Disc Image File

Disk Image Files

M3U file extension

Media Playlist File

Audio Files

PS file extension

PostScript File

Vector Image Files

PY file extension

Python Script

Developer Files

SRT file extension

SubRip Subtitle File

Video Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TMP file extension

Temporary File

Backup Files

TTF file extension

TrueType Font

Font Files

YUV file extension

YUV Encoded Image File

Raster Image Files