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

AI file extension

Adobe Illustrator File

Vector Image Files

APK file extension

Android Package File

Executable Files

ASF file extension

Advanced Systems Format File

Video Files

CPP file extension

C++ Source Code File

Developer Files

CSR file extension

Certificate Signing Request File

Web Files

DTD file extension

Document Type Definition File

Developer Files

ICNS file extension

Mac OS X Icon Resource File

System Files

PART file extension

Partially Downloaded File

Misc Files

PHP file extension

PHP Source Code File

Web Files

SLN file extension

Visual Studio Solution File

Developer Files

VCD file extension

Virtual CD

Disk Image Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WPD file extension

WordPerfect Document

Text Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files