Neutral Atomic Hydrogen Surveys: past, present and future

Abstract: Neutral atomic hydrogen (HI) observations are fundamental to understand the dynamics of galaxies, their assembly, the fuelling of their star formation and environmental interactions. HI studies have so far been limited by the capabilities of single-dish radio telescopes or synthesis arrays to either small samples or low resolution and sensitivities. Now, the Square Kilometer Array precursors and pathfinders are providing a novel view of the HI in and around galaxies allowing wide-field high resolution deep surveys in nearby galaxies. We give an overview of past, current and future HI surveys consistently comparing their HI column density and spatial resolutions highlighting their main scientific key goals and results.