Hi,
I would like to know the difference between mp3 and mp4 ? Any useful notes about these format ?

BAsically
MP3 is for sound files (see here:http://all-streaming-media.com/streaming-media-faq/faq-Description-of-popular-audio-formats-MP3-WMA-OGG-AAC-WAV.htm )


And

MP4 is for video and sound (see here: http://all-streaming-media.com/streaming-media-faq/faq-mp4-streaming.htm )

Hope this helps

Hi,
This link:

http://channels.lockergnome.com/windows/archives/20051028_mp3_or_mp4.phtml

Has a very good explanation, and short history, of both MP3 and MP4.
The MP4 is only used through itunes and ipods, but the MP3 is a "standard" for most players and converters.

Fred was a little off when he said "MP4 is only used through itunes and ipods". That's the audio-only part of mp4 also known as AAC in the iTunes world. Mp4s are also related to video content as well: http://en.wikipedia.org/wiki/Mp4