What is The NWOBHM Exactly & What Was The First/Old Wave?

Here I talk about what the NWOBHM is and the confusing aura or hype is concerning this "wave" of music that began with the decline of punk in the mid to late 70's. In addition, since this is the "New" wave, what was the Old or First wave of British Heavy Metal? #nwobhm #heavymetal #heavymetalfans