What is BLU-RAY /DISK ? Real Difference between DVD & BLU-RAY ! DETAILED EXPLANATION !!!

HERE ITS ALL ABOUT BLU -RAY AND BD DISKS AND ITS TYPES AND WHAT ARE THE DIFFERENCES BETWEEN DVD AND BLU RAY . THERES ALSO SOME OTHER THINGS IN DETAIL ABOUT THE WORKING OF BLUE RAY DISK AND DVD . BLU-RAY VS DVD, COMPARISON,STORAGE ,QUALITY ETC