In the previous modules, we have discussed much of the physics as it relates to the production of artifacts. In this chapter, we formalize the physics concepts through examples and our discussion of the underlying principles. In essence, artifacts are generated whenever an assumption of ultrasound is violated. In this module, we discuss the imaging artifacts of limited detail resolution, reverberation, grating lobes, refraction, shadowing, enhancement, multi-path, and mirroring. Once the imaging artifacts have been reviewed, we discuss Doppler artifacts such as aliasing, wall filter saturation, spectral broadening, blooming or blossoming, and flash.