Data File Formats and File Extensions

Ever encounter a file extension you’ve never seen before? Check this page for more 3,700 data formats and their corresponding file extensions.

Webopedia’s Guide to File Formats & Extensions

In the list below, search for a file extension by the letter it starts with or you can view the complete list of more than 3,700 file extensions.

Number Symbol A B C D E F G H I J K
L M N O P Q R S T U V W X Y Z Full List

Data Files Related Terminology

The following data files and formats glossary will help you to better understand how files are stored and are accessed on your computer.

What is a File Format?

File format is a format for encoding information in a file. Each different type of file has a different file format. The file format specifies first whether the file is a binary or ASCII file, and second, how the information is organized.

What is a Filename?

All files have names. The name if a file is its filename. Different operating systems impose different restrictions on filenames. Most operating systems, for example, prohibit the use of certain characters in a filename and impose a limit on the length of a filename. In addition, many systems allow a filename extension that consists of one or more characters following the proper filename. The file extension usually indicates what type of file it is.

What is a File Extension?

File extension is one or several letters at the end of a filename. Filename extensions usually follow a period (dot) and indicate the type of information stored in the file. For example, in the filename EDIT.COM, the extension is COM, which indicates that the file is a command file. Depending on the operating system, the punctuation separating the extension from the rest of the filename may or may not be considered part of the extension itself.

What is a Pathname?

The pathname is a sequence of symbols and names that identifies a file. Every file has a name, called a filename, so the simplest type of pathname is just a filename. If you specify a filename as the pathname, the operating system looks for that file in your current working directory. However, if the file resides in a different directory, you must tell the operating system how to find that directory. You do this by specifying a path that the operating system must follow.

Editor’s Recommendation: See Webopedia’s Data Formats category for related terms and their definitions.

This article was originally published on May 29, 2009

Webopedia Staff
Webopedia Staff
Since 1995, more than 100 tech experts and researchers have kept Webopedia’s definitions, articles, and study guides up to date. For more information on current editorial staff, please visit our About page.

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