The smallest fluid on Earth

High energy heavy ion collisions create quark gluon plasmas that behave like almost perfect fluids. Very similar features to those led this insight have also been observed in experimental data from of small systems, involving protons or other light nuclei. We describe recent developments aimed at understanding whether, and if so how, systems produce relatively few particles (orders magnitude less than typical collisions) are only one a times the size proton, can This involves deeper fluid dynamics its applicability, improvements our initial geometry by considering fluctuations proton shape, as well advancements calculation state effects within an effective theory quantum chromodynamics, which affect observables used study behavior. further address open questions discuss future directions.