A Casino Host, sometimes called Slot Host, Table Host, Player Development Executive are an employee of the Casino hired to sell it's service's, of which the primary one is gaming. Such as dinner in the buffet or gourmet restaurant, show tickets, special events and a host of other services. Every time you play at a casino, your wagering is being tracked by the casino's player rating system through your player rating card you placed in the slot machine or handed to a Floor Person in the gaming pit area.
Many variables make up how a player rating is determined.
The most important is the time and amount of your wagering. On a slot machine this means the amount of coins you put in per pull. On table games it's the amount of your bet. Other factors can include but not limited to pulls per minute and denomination of the slot machine. A Casino Host is the person who issues complimentaries.