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

CSR file extension

Certificate Signing Request File

Web Files

DB file extension

Database File

Database Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

7Z file extension

7-Zip Compressed File

Compressed Files

CLASS file extension

Java Class File

Developer Files

ICNS file extension

Mac OS X Icon Resource File

System Files

XCODEPROJ file extension

Xcode Project

Developer Files

APK file extension

Android Package File

Executable Files

PPS file extension

PowerPoint Slide Show

Data Files

BIN file extension

Binary Disc Image

Disk Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

CS file extension

Visual C# Source Code File

Developer Files

TXT file extension

Plain Text File

Text Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files