Get Familiar with these extensions

Sound:

MPEG-1/2 Audio Layer 3 (.mp3)
Ogg Vorbis (.ogg)
ASF Audio (.asf,.wma)
Wave form audio format (.wav)
RealAudio (.ra,.rm)
Free Lossless Audio codec(.flac)
Advanced Audio coding (.aac)
MPEG-4 advanced audio coding (.m4a,.mp4)
Musepack (.mpc)
TwinVQ(.vqf)
3GP Music (.3gp)
AC3 Audio File (.ac3)
Adaptive Multi-Rate (.amr)
Adaptive Multi-Rate WB (.awb)
Sun Mircrosystem's audio format (.au,.snd)
Audio Interchange File Format (.aiff)
Purevoice File (.qcp)
AMIGA 8bit sound file (.8svx)
PSION sound file (.prc)
IRCAM sound file (.sf)
soundTool (.sndt)
PSION 8bit sound file (.wve)
soundtracker module (.mod)
FastTracker II module (.xm)
ImpulseTracker module (.it)
ScreamTracker module (.s3m)

Ringtone (Monophonic/Polyphonic):

MIDI-0 (.mid,.midi)
SP-MIDI (.mid,.midi)
Midi Karaoke (.kar)
MMF/SMAF-1 (.mmf,.smaf)
Qualcomm CMX 3.0 (.pmd)
Motorola Ringtone (.mot)
Sagem Ringtone (.sagem)
Sagem Ringtone (.sagem21)
Ericsson emelody (.emy)
iMelody Ringtone Format (.imv)
Ringtones text transfer language (.rttl,.rtx)
Nokia phone Ring Tone (.nokia,.ott)
Nokia Phone Ring Tone (.noktxt)

Image:

Joint photographic experts group (.jfif,.jif,.jpe,.jpeg,.jpg)
Windows bitmap (.bmp)
Graphics interchange format (.gif)
Truevision TGA (.tga)
Portable network graphics (.pgm)
AVS X image (.avs)
Kodak Cineon Image Format (.cin)
ZSoft IBM PC multi-page paintbrush (.dcx)
Windows device independent bitmap (.dib)
SMPTE digital moving picture exchange (.dpx)
Microsoft icon (.ico)
Magick image file format (.miff)
On-the-air-Bitmap (.otb)
Palm pixmap (.palm)
Portable bitmap format black/white (.pbm)
Xv's Visual Schnauzer thumbnail (.p7)
Photo CD (.pcd)
Zsoft IBM PC Paintbrush file (.pcx)
Apple Mcintosh QuickDraw (.pict)
Portable Pixmap format - color (.ppm)
Adobe Photoshop bitmap file (.psd)
Photo CD - sRGB color (.pcds)
Irix RGB image (.sgi)
SUN Raster Image (.ras,.sun)
X Windows system bitmap black/white (.xbm)
X Windows system pixmap (.xpm)
CCIR 601 4:1:1 (.yuv)

Vector Document:

Windows Metafile (.wmf)
Scalable Vector Graphics (.svg)
Magick Vector Graphics (.mvg)
AutoCAD Interchange Format (.dxf)
Enhanced Metafile (.emf)
Encapsulated Postscript (.eps)
Computer Graphics Metafile (.cgm)
OS/w Metafile (.met)
OpenOffice 2.0 Draw Document (.odg)
OpenOffice 2.0 Draw Template (.otg)
OpenOffice 1.0 Draw Document (.sxd)
OpenOffice 1.0 Draw Template (.std)

Document:

Text files (.txt)
Url address (web) (.url)
HyperTextMarkup Language (.htm,.html)
XHTML (.xhtml)
Rich Text Format/MS Word (.rtf)
Portable Document Format (.pdf)
Adobe Postscript (.ps)
Microsoft Word (.doc)
MS Word template (.dot)
OpenOffice 2.0 Text Document (.odt)
OpenOffice 2.0 Text Template (.ott)
OpenOffice 1.0 Text Document (.sxw)
OpenOffice 1.0 Text Template (.stw)
AportisDoc Palm DB (.pdb)
Starwriter vorlage/Template (.vor)
PocketWord (.psw)
Wordperfect 6 (.wpd)
MS Word 2003 XML (.xml)

Data:

Data Interchange Format (.dif)
dBASE (.dbf)
Microsoft Excel (.xls)
MS Excel Vorlage/Template (.xlt)
Pocket Excel (.pxl)
SYLK (.slk)
Lotus 1-2-3 (.123,.wk1)
StarCalc (.sdc)
StarCalc Template (.vor)
OpenOffice 2.0 Spreadsheet (.ods)
OpenOffice 2.0 Calc template (.ots)
OpenOffice 1.0 spreadsheet (.sxc)
OpenOffice 1.0 calc template (.stc)

Mathematics:

MathML (.mml)
StarMath (.smf)
OpenOffice 2.0 Math (.odf)
OpenOffice 1.0 Math (.sxm)

Presentation:

Microsoft Powerpoint (.ppt)
Microsoft Powerpoint Template (.pot)
StarImpress 5.0 (.sdd)
StarImpress 5.0 Template (.vor)
StarImpress 4.0 (.sdd)
StarImpress 4.0 Template (.vor)
OpenOffice 2.0 Impress (.odp)
OpenOffice 2.0 Impress Template (.otp)
OpenOffice 1.0 Impress (.sxi)
OpenOffice 1.0 Impress Template (.sti)

Compressed archives:

Data compression (.zip)
7Z Archive (.7z)
LHA Archive (.lha,.lzh)
Roshal ArchiveArchive (.rar)
Tape ARchive (.tar)
TAR Gzip Compressed archive (.gz)
BZ2 compressed archive (.bza)
Deepfreezer YZ1 archive (.yz1)

Movie:

Windows Media Video (.wmv)
3GP/3G2 Video (.3gp)
Audio Video Interleave (.avi)
Matroska (.mkv)
Apple Quicktime (.mov)
Motion Picture Expert Group (.pg)
Ogg vorbis Compressed video (.ogm)
MPEG-4 (.mp4)
Flash Video (.flv)
DVD Video Object (.vob)
FLIC Animation (.fli)
Digital Video (.dv)
ASF Video (.asf)
Google Video File (.gvi)