Blue Ray Rw What Exactly Is A Lightscribe Blu-Ray ROM With SuperMulti DVD+/-R/RW Double Layer?

What exactly is a Lightscribe Blu-Ray ROM with SuperMulti DVD+/-R/RW Double Layer? - blue ray rw

I buy a new laptop, an HP HDX18t. I am a little confused about the Blue-Ray ROM. Double layer is said, is that it's both a Blu-ray and DVD? I will be able to play regular DVD's right?
I understand that to burn the LightScribe and the creation of the film / music vids not my confusion.
Thank you!