
Some of the common file types are:
Productivity
Plain text (.txt), rich text (.rtf), Word (.doc), Dbase (.dbf), Excel (.xls),PageMaker (.pm3, 4, 5, 6), PowerPoint (.ppt), Quark XPress (.qxd),Quicken (.qdf)
Media:
MP3 (.mp3), AAC (.aac), AIFF (.aiff), ASF (.asf), AVI (.avi), MIDI (.midi),MPEG1, MPEG 2, and MPEG 4 video (.mpg, .mp2, .mp4), QuickTimeMovie (.qt, .mov), Real Audio/Video (.ra, .ram), Wave Form Audio(.wav), Windows Media Audio and Video (.mwa, .wmv)
Graphics
BMP (.bmp), GIF (.gif), JPEG (.jpg), TIFF (.tif), PICT (.pct), EPS (.eps),Photoshop (.ps), PostScript (.ps), PDF (.pdf)
Internet
HTML (.html, .htm), MIME (.mim, .mime), XML (.xml)
Compression
Stuffit (.sit) and ZIP (.zip)Filename extensions are usually hidden in Mac OS X. To show thefilename extension for all files, choose Finder > Preferences andselect “Always show file extensions.”