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

BAK file extension

Backup File

Backup Files

CUR file extension

Windows Cursor

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

HTML file extension

Hypertext Markup Language File

Web Files

JS file extension

JavaScript File

Web Files

PPT file extension

PowerPoint Presentation

Data Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RA file extension

Real Audio File

Audio Files

RTF file extension

Rich Text Format File

Text Files

SITX file extension

StuffIt X Archive

Compressed Files

SQL file extension

Structured Query Language Data File

Database Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files

3GP file extension

3GPP Multimedia File

Video Files