what does "type='audio/ogg' " means.?? why it is used here?

Answer 1

It is another type of audio format just like we have mp3, Wav and apparently ogg, the type there is specifying the type of format for the audio file

Answer 2

and if you include unknown format then it will try to play via one of these formats. if not supported then the text between audio tag is displayed.

Answer 3

html5 supports audio files as mp3,wav or ogg.in this case we are specifying the type of audio file included