Why MP4 format is gives first and then ogg ?? And what mean of ogg ??

Answer 1

If you put OGG, it works in internet explore...

Answer 2

https://www.sololearn.com/learn/HTML/2194/?ref=app

Check the comments section there, you will find useful information

Answer 3

If the browsers do not support the first file format it will use the other file format.