This document discusses common file extensions used in different file types. It provides examples of extensions for text files (.doc, .txt), audio files (.mp3, .wav), video files (.avi, .mpg), image files (.jpg, .png), spreadsheet files (.xls, .xlsx), database files (.mdb, .sql), game files (.nes, .sav) and more. It also discusses recommended file formats for digital libraries, including .pdf, .ppt, .jpg, .tif, .mpg, .png, .avi, .wav and .aif and .mp3.

1. FILE EXTENSIONS
Prepared by:
Bartolome, Cristobal
Polking, Judy-an

2. FILE EXTENSIONS
also known as file name extension.
a file extension (or simply "extension") is the
suffix at the end of a filename that indicates
what type of file it is.
is a set of characters that helps Windows
understand what kind of information is in a file
and what program should open it.

5. Common File
Extensions

6. TEXT FILES
 .doc - Microsoft Word Document . A word
processing document created by Microsoft Word;
may contain formatted text, images, tables,
graphs, charts.
 .docx - Microsoft Word Open XML Document.
Unlike .DOC files, which store document data in
a single binary file, DOCX files are created using
the Open XML format, which stores documents
as a collection of separate files and folders in a
compressed zip package.

7.  .log – Log File. May be created by the operating
system to keep track of system events or by a
software installation program to list location and
names of installed files.
.odt – OpenDocument Text Document.
OpenDocument text files can be opened and edited
with any OpenOffice-compatible program,
including: NeoOffice (Mac), AbiWord (Mac &
Windows), and KWord (Unix). They can also be
imported into Google Docs, Google's Web-based
word processor and spreadsheet application.

8. .msg – Outlook Mail Message. Message created
or saved within Microsoft Outlook; contains
multiple e-mail fields, including the date, sender,
recipient, subject, and message body.
 .rtf – Rich Text File Format. May include
several types of text formatting, such as bold
type, italics, different fonts and font sizes,
custom tab settings, etc; may also support images
saved within the text file.

9.  .txt – Plain Text File. Standard text document
that contains unformatted text; recognized by any
text editing or word processing program; can also
be processed by most other software programs.
.wpd – WordPerfrct Document. Created by Corel
WordPerfect, may contain formatted text, tables,
drawn objects, and images; stored in a
proprietary Corel format, but can be exported to
other formats from within WordPerfect.

10.  .wps - Microsoft Works Word Processor
Document. Document created with Microsoft
Works word processing software; similar to a
Microsoft Word (.DOC) document, but does not
include advanced formatting options and macros
that a Word document may contain.

12. AUDIO FILES
 .aif – Audio Interchange File Format. Audio file
created using the Audio Interchange File Format
(AIFF); contains uncompressed CD-quality
audio, similar to a .WAV file; commonly used to
store standard CD audio.
.m4a – MPEG-4 Audio File. A multimedia
container format used to store compressed audio
and video data.

13.  .mid – MIDI File (Musical Instrument Digital
Interface). Contain attributes of music data rather
than music data itself. They can be played back
using software instruments that interpret this
data.
 .mp3 - MP3 Audio File. Commonly used to store
music files and audiobooks on a hard drive. The
quality of an MP3 file depends largely on the bit
rate used for compression.

14.  .wav – WAVE Audio File. A standard digital
audio file format used for storing waveform
data.
 .wma – Windows Media Audio File. Can be
converted to other more standardized formats;
often used for playing music from the Web.

16. DATA FILES
 .dat – Data File. It is used by Piriform
applications to recognize that it should operate in
portable mode.
 .pps – PowerPoint Slide Show. Created with
Microsoft PowerPoint, a common program for
creating presentations; saved as a completed
slide show, which can be viewed by either
PowerPoint or PowerPoint Viewer.

17.  .ppt – PowerPoint Presentation. Editable slide
show created with Microsoft PowerPoint; often
used for presentations or slideshows.
.pptx – PowerPoint Open XML Presentation. File
types in PPTX files are also more accessible than
those in PPT files.
 .sdf – Standard Data File. Compact relational
database developed by Microsoft; designed for
applications that run on mobile devices and
desktops; contains the complete database
contents and can be up to 4GB in size.

18.  .xml – XML File. XML (Extensible Markup
Language) data file that uses tags to define
objects and object attributes; formatted much like
an .HTML document, but uses custom tags to
define objects and the data within each object;
can be thought of as a text-based database.

20. VIDEO FILES
 .3gp – 3GPP Multimedia File. Developed by the
3rd Generation Partnership Project (3GPP);
designed as a multimedia format for transmitting
audio and video files between 3G cell phones and
over the Internet.
 .asf – Advanced Systems Format File. A
proprietary video and audio container format;
developed by Microsoft primarily
for streaming media; contains audio and video
data and optionally metadata, such as title,
author, and copyright bibliographic data.

21.  .avi – Audio Video Interleave File. A format
created by Microsoft; stores video data that may
be encoded in a variety of codecs. AVI files can
be played by various video players, but the
player must support the codec used to encode the
video data.
 .flv – Flash Video File. Consists of a short
header, interleaved audio, video,
and metadata packets. The FLV format is an open
format that is also supported by non-
Adobe/Macromedia programs.

22.  .mp4 – MPEG-4 Video File. Commonly used for
sharing video files on the Internet. MP4 files are
supported by many video programs and various
hardware devices, such as the Apple iPod portable
media player.
 .mpg – MPEG Video File. Common digital video
format standardized by the Moving Picture Experts
Group (MPEG). Is often used for creating movies
that are distributed on the Internet.

23.  .wmv – Windows Media Video File. A video file
based on the Microsoft Advanced Systems Format
(ASF) and compressed with Windows Media
compression. Similar to an .ASF file and contains
video encoded with one of Microsoft's Windows
Media Video (WMV) proprietary codecs.

24. IMAGE FILES
 .jpg – JPEG Image File. The most used image file
format. Commonly used for storing digital photos
since the format supports up to 24-bit color;
therefore, most digital cameras save images as JPG
files by default.
 .gif – Graphical Interchange Format File. Are
common format for Web graphics, especially small
images and images that contain text, such as
navigation buttons.

25.  .png – Portable Network Graphic. The PNG format
was created in response to limitations with the GIF
format, primarily to increase color support and to
provide an image format without a patent license.
 .psd – Adobe Photoshop Document. Image file
created by Adobe Photoshop, which may include
image layers, adjustment layers, layer masks,
annotation notes, file information, keywords, and
other Photoshop-specific elements.

26.  .tif – Tagged Image File. Short for ‘.TIFF.’ A high-
quality graphics format often used for storing
images with many colors, such as digital photos.

28. SPREADSHEET FILES
 .xlr – Works Spreadsheet. A popular productivity
suite; stores data in cells that are organized in a grid
consisting of rows and columns.
 .xls – Excel Spreadsheet. A spreadsheet created by
Microsoft Excel, the most widely-used spreadsheet
program; stores data in a table with rows and
columns, often used to create charts and graphs.

29.  .xlsx – Microsoft Excel Open XML Spreadsheet. A
program used to create spreadsheets; stores data in
worksheets. Commonly used to store financial data
and to create simple or complex mathematical
models.

31. DATABASE FILES
 .accdb – Access 2007 Database File. A
database created with Microsoft Access 2007;
typically contains data organized into tables and
fields.
 .db – Database File. A database file used on mobile
devices such as Android, iOS, and Windows Phone
7; often stores contacts and SMS information but
may store any type of device or application data.

32.  .mdb – Microsoft Access Database. Created by
Microsoft Access, a widely-used desktop relational
database program; contains the database structure
and database entries as well as data entry forms,
queries, stored procedures, reports, and database
security settings.
.pdb – Program Database. Are usually saved in a
proprietary format, meaning they can only be
opened by the program they were installed with.

33.  .sql – Structueed Query Language Data. Contains
SQL code used to modify the contents of a relational
database; may contain statements for creating or
modifying database structures, or may contain
insertions, updates, deletions, and other SQL
operations.

35. GAME FILES
 .gam – Saved Game File. A file created by various
video games to store saved games; may be manually
saved by the user or automatically saved by the
program.
 .nes – Nintendo(NES) ROM File. Created from an
NES (Nintendo Entertainment System) video game;
contains the same data as the original NES
cartridge; can be opened and played on a Mac or PC
using an NES emulator.

36.  .sav – Nintendo DS Save File. Created for games
on the Nintendo DS portable game system; may
include game information such as the character
name, experience points, completed levels, and in-
game resources; stores the state of the current game
progress.
 .dem – Video Game Demo File. A game replay file
created by various first-person shooter games and
most popularly by Counter-Strike, used for sharing
replays with others.

37. WEB FILES
 .html – Hypertext Markup Language File. Web
page used by Web browsers; contains markup code
that is stored on a plain text format; used to display
and format text and images in a Web browser.
.php – Hypertext Preprocessor File. May include
PHP functions that can process online forms, get the
date and time, or access information from a
database.

38. The HTML, which contains the Web page content, is
then sent to the user's Web browser. Therefore, the
user never sees the actual PHP code contained in the
Web page, even when viewing the page source.
 .xhtml – Extensible Hypertext Markup Language
File. Uses standard HTML tags, but must conform
to more strict XML guidelines.

39.  .js – JavaScript File. Text file
containing JavaScript code; used to execute
JavaScript instructions in Web pages. Referenced by
Web pages that incorporate JavaScript functions.
Usually imported in the . Section of the HTML.
 .jsp – Java Server Page. Contains Java code instead
of ActiveX or PHP; the code is parsed by the Web
server, which generates HTML that is sent to the
user's computer.

41. BACKUP FILES
 .bak – Firefox Bookmarks Backup. Can be used to
replace saved bookmarks in case the main
bookmarks file becomes corrupted; automatically
generated by the Firefox Web browser.
 .tmp – Temporary File. Created automatically by a
software program; usually serves as a backup or
cache file; sometimes created as an invisible file and
is often deleted when the program is closed.

42. OTHER COMMON FILE
FORMATS
 .pdf – Portable Document Format. A file format
that has captured all the elements of a printed
document as an electronic image that you can
view, navigate, print, or forward to someone else.

43. DIGITAL PRESERVATION
The aim of digital preservation is to ensure that
digital records are filed and are made available
throughout time.
Each digital library consists of different
documents with different file formats.

44. RECOMMENDED FILE
FORMATS FOR
DIGITAL LIBRARIES

45.  .pdf
 .ppt
 .jpg
 .tif
 .mpg
.png
 .avi
 .wav
 .aif
 .mp3

46. REFERENCES:
http://fileinfo.com/filetypes/common
http://it.nmu.edu/docs/common-windows-
file-extensions