The steady interest in miniaturizing optical systems ultimately leads to flat optics, which includes any concept to reduce the thickness of components and systems by introducing surfaces with high functionality. In this online seminar we invite you to join us on a journey through the concepts, prospects, challenges, and myths of the different versions of flat components, with an emphasis on lenses. The journey starts with discussing the most fundamental goal in optical design, that is, controlling and manipulating the wavefront of the light which enters an optical system. While in imaging optics spherical wavefronts are desired and aberrations should be minimized, in light shaping tailored aberrations should be introduced. In the next stop on the journey we discuss ways to realize required wavefront phase manipulations by optical surfaces. We start with the design of freeform surfaces. Then, we turn to flat optics in the form of diffractive, Fresnel-type and meta surfaces. The webinar will conclude with a Q&A.