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

EPS file extension

Encapsulated PostScript File

Vector Image Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

INDD file extension

Adobe InDesign Document

Layout Files

JAR file extension

Java Archive File

Executable Files

MAX file extension

3ds Max Scene File

3D Image Files

PDF file extension

Portable Document Format File

Layout Files

PPS file extension

PowerPoint Slide Show

Data Files

PS file extension

PostScript File

Vector Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TMP file extension

Temporary File

Backup Files

TOAST file extension

Toast Disc Image

Disk Image Files

WSF file extension

Windows Script File

Executable Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files

3DS file extension

3D Studio Scene

3D Image Files