An aquifiller is a type of geological formation that can store and transmit water, typically composed of permeable materials like sand, gravel, or fractured rock. It serves as a reservoir for groundwater, allowing water to flow through its pores or fractures. Aquifillers are crucial for water supply, irrigation, and maintaining ecosystems, as they help recharge aquifers and sustain surface water bodies. Their characteristics, such as porosity and permeability, determine their efficiency in water storage and movement.