Largely a combination of flavoring spices used along with taste-agents like black pepper & chili to impart a pleasantly textured flavor to ordinary rice.
The origins of this blend can be traced back to the Mughal era.
Biryani/Pulav can either be a Veg. or a Non-Veg. preparation usually made during special occasions. It is a whole meal by itself, and is almost always the Centre-piece of most Indian dinner parties. Is usually served with curry and raita (curd spiked with fresh green herbs)