HDD = Hits Daily Double http://www.hitsdailydouble.com/

 

KAndre's definition:  HDD is one of the older and "more reliable" music industry gossip rags, lots of insider info - but usually have excellent rough estimates of CD sales...they got updates throughout the day on Tuesday and Wednesday and we used to watched the numbers roll in. Click on the hillbilly's bouncing head, give a fake name and company and a dummy spam email account and you're set to go.