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

CAB file extension

Windows Cabinet File
System Files

CLASS file extension

Java Class File
Developer Files

DMP file extension

Windows Memory Dump
System Files

GZ file extension

Gnu Zipped Archive
Compressed Files

LNK file extension

Windows File Shortcut
System Files

MDB file extension

Microsoft Access Database
Database Files

PRF file extension

Outlook Profile File
Settings Files

PSPIMAGE file extension

PaintShop Pro Image
Raster Image Files

SLN file extension

Visual Studio Solution File
Developer Files

THM file extension

Thumbnail Image File
Raster Image Files

TMP file extension

Temporary File
Backup Files

WMA file extension

Windows Media Audio File
Audio Files

WPS file extension

Microsoft Works Word Processor Document
Text Files

XML file extension

XML File
Data Files

7Z file extension

7-Zip Compressed File
Compressed Files