Groundwater is the naturally occurring water held underground in the pores and spaces of the earth, infiltrating through precipitation and surface runoff. This subterranean reservoir exists in saturated zones, which are typically found within porous geological formations such as unconsolidated sediments, fractured bedrock, and karst systems. The movement and availability of groundwater are governed by principles of hydrology, depending on factors like permeability, porosity, and the hydraulic gradient. It serves as a critical source of freshwater for human consumption, agriculture, and industrial use, and its quality can vary significantly based on the geological makeup of the confining strata, potentially containing dissolved minerals and naturally occurring contaminants.