Speaker: Wolf von Klitzing (ULF-FORTH) The famous particle-wave duality states that all particles are waves and all waves are particles. Most of us are aware of the fact that light can be thought of consisting of photons. It is less well known that atoms can behave just like (matter)waves, which can be manipulated in a manner analogous to light: We now can create matterwave lenses, waveguides, interferometers and even matterwave amplifiers and lasers. In this colloquium, I will introduce the basics of matterwave (optics) as well as some of its applications to precision sensing. I will also present some of the research results of the Cretan Matterwaves Group, where we have demonstrated a CERN-like matter-wave accelerator and fully-coherent matterwave guide [1] as well as matterwave-lensing down to the pico-kelvin regime.