Models, as well as the explanations and predictions they produce, are on everyone's minds these days, due to the climate crisis and the Corona pandemic. But how do these models work? How do they relate to experiments and data? Why and how can we trust them and what are their limitations? As part of the omega tau podcast, I have asked these questions of dozens of scientists and engineers. Using examples from medicine, meteorology and climate science, experimental physics and engineering, this talk explains important properties of scientific models, as well as approaches to assess their relevance, correctness and limitations.