Rubs. What the hell is a rub? Well a rub is any dry spice mix that is put on the meat prior to the meat being put on the grill. Some people shake their rub on the meat - like using a salt shaker. Others rub it into the meat massaging every inch, clogging every pore with their spices.
Rubs offer a lot of flavor and help keep in the moisture.
Here's a link about rubs...
Using Rubs and Spices the Right Way