Hotels mostly offer discounts to attract more customers. So, you pay less than the usual charges, charged on other days. However discount hotel booking is not made available during holidays or other special time of the year. This is because this is the time when the hotels are near fully occupied.
Hotels fix the charges based on demand for rooms. During peak periods, they charge more. But during off seasons they are willing to offer discounts. When the demand for rooms comes down, many rooms remain unoccupied. However for those who visit the hotel all round the year, like corporate executives, discounts are provided irrespective of the season.