Storage, mixing, ascent and eruption of magma involve complex interactions and feedbacks between different physical and chemical processes. Studies of eruption products guide the development of concepts and provide ground-truth for models. Field investigations of deposit architectures constrain eruptive histories, depositional mechanisms, and eruption durations; measurements allow quantification of eruption parameters using increasingly elaborate inverse models of plumes and ground-hugging flows. Morphological descriptions of pyroclasts give constraints on mechanisms of magma emplacement and fragmentation. Textural analysis, including sub-micron-resolution tomography, provides increasingly rapid and accurate characterization of crystal and vesicle cargos, allowing estimates of parameters such as magma-storage durations, syn-eruptive ascent speeds and rates of permeability acquisition as dissolved gases exsolve. Sophisticated microbeam techniques allow analysis of volatiles, trace elements and isotopes in crystals, melt inclusions and interstitial glasses, providing information on pre-eruptive parameters, degassing and crystallization histories, and conduit processes. Elemental gradients in crystals and glasses provide access to timescales of magma storage, mixing and ascent. Integration of field and laboratory techniques offers ways of better understanding the processes underpinning different eruption regimes and regime transitions. This session will bring together presentations on these and other modern techniques of quantitatively characterizing the products of magmatic and volcanic processes in order to constrain process dynamics, from magma chambers to dispersal in the atmosphere.