The document discusses various drought indices and their inputs, such as precipitation, temperature, soil moisture, and evapotranspiration. It also discusses the Palmer Drought Severity Index, Palmer Hydrological Drought Index, Crop Moisture Index, Surface Water Supply Index, Percent of Normal Precipitation, Deciles, and Standardized Precipitation Index. The document notes that these indices integrate large amounts of data to monitor drought severity comprehensively and measure climate deviations from normal conditions.