Whether you are Agile or Waterfall, you want testability. Whether you release periodically or continuously, you want testability. Testability means how easily a product can be tested. In other words, do bugs hide from you, lurking deep in the folds of your technology? Or do they run out and surrender when you come by, while wearing bright reflective vests? This talk is about how to think about practical testability, which has five aspects: Epistemic, Subjective, Value-Related, Project-Related, and Intrinsic.