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

ASP file extension

Active Server Page

Web Files

DBF file extension

Database File

Database Files

DOC file extension

Microsoft Word Document

Text Files

GADGET file extension

Windows Gadget

Executable Files

INI file extension

Windows Initialization File

Settings Files

JAR file extension

Java Archive File

Executable Files

MDB file extension

Microsoft Access Database

Database Files

PDF file extension

Portable Document Format File

Layout Files

PPS file extension

PowerPoint Slide Show

Data Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RTF file extension

Rich Text Format File

Text Files

SDF file extension

Standard Data File

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files