Much like a DOC file is a type of file used for word processing documents and a JPG file is a file used for photographs, an MP3 file is used for songs.
The format is still in the popular JPG style, which is just fine for the iPhone.
At LCARS Blueprints Database, you will find a huge collection of blueprints in JPG format, which means they aren't badly scanned in copies.
Using graphical solutions solves those compatibility problems, since every browser can display a GIF or JPG file.
The Nook supports a wide range of e-book formats, including ePub, BBeB, Adobe PDF, XLS, DOC, PPT, PPS, TXT, DOCM, XLSM, PPTM, PPSX, PPSM, DOCX, XLSX, PPTX, JPG, GIF, PNG, BMP, MP3, AAC and MP4 formats.