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

SQL file extension

Structured Query Language Data File

Database Files

RA file extension

Real Audio File

Audio Files

PDF file extension

Portable Document Format File

Layout Files

APP file extension

Mac OS X Application

Executable Files

MPA file extension

MPEG-2 Audio File

Audio Files

M file extension

Objective-C Implementation File

Developer Files

VOB file extension

DVD Video Object File

Video Files

MDB file extension

Microsoft Access Database

Database Files

TTF file extension

TrueType Font

Font Files

CAB file extension

Windows Cabinet File

System Files

RM file extension

Real Media File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

TIFF file extension

Tagged Image File Format

Raster Image Files

HTML file extension

Hypertext Markup Language File

Web Files

FLA file extension

Adobe Flash Animation

Developer Files