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

ACCDB file extension

Access 2007 Database File

Database Files

BIN file extension

Binary Disc Image

Disk Image Files

CLASS file extension

Java Class File

Developer Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CUE file extension

Cue Sheet File

Disk Image Files

IFF file extension

Interchange File Format

Audio Files

JS file extension

JavaScript File

Web Files

LOG file extension

Log File

Text Files

MP3 file extension

MP3 Audio File

Audio Files

MPA file extension

MPEG-2 Audio File

Audio Files

PHP file extension

PHP Source Code File

Web Files

PL file extension

Perl Script

Developer Files

VCD file extension

Virtual CD

Disk Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files