A "Water Column" refers to a vertical section of water that extends from the surface down to the bottom of a body of water, such as an ocean, lake, or river. It is used to study various physical, chemical, and biological properties of water at different depths. Scientists often analyze the water column to understand temperature, salinity, and nutrient distribution, which are crucial for aquatic ecosystems. In oceanography, the water column is essential for understanding marine life and ocean currents. Instruments like CTD sensors (Conductivity, Temperature, Depth) are deployed to collect data throughout the water column, helping researchers monitor changes in the environment and assess the health of aquatic habitats.