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

BAT file extension

DOS Batch File

Executable Files

CPL file extension

Windows Control Panel Item

System Files

CUR file extension

Windows Cursor

System Files

MAX file extension

3ds Max Scene File

3D Image Files

MSG file extension

Outlook Mail Message

Text Files

ODT file extension

OpenDocument Text Document

Text Files

PIF file extension

Program Information File

Executable Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RM file extension

Real Media File

Video Files

RTF file extension

Rich Text Format File

Text Files

SLN file extension

Visual Studio Solution File

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

TIFF file extension

Tagged Image File Format

Raster Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files