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

BIN file extension

Binary Disc Image

Disk Image Files

DMP file extension

Windows Memory Dump

System Files

ICNS file extension

Mac OS X Icon Resource File

System Files

KMZ file extension

Google Earth Placemark File

GIS Files

IFF file extension

Interchange File Format

Audio Files

VCD file extension

Virtual CD

Disk Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

ZIP file extension

Zipped File

Compressed Files

UUE file extension

Uuencoded File

Encoded Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

RTF file extension

Rich Text Format File

Text Files

CSR file extension

Certificate Signing Request File

Web Files

MOBI file extension

Mobipocket eBook

eBook Files

GBR file extension

Gerber File

Data Files