We know the electron from everyday life: electrons travelling in metallic conductors form the electric current. They are therefore at the basis of innumerable technical applications, from cell phones to electric cars. Visualising an electron requires however to go at the boundaries of imagination. An electron is namely not a small sphere, but rather the concentration of an energy field into a point. Neither do electrons orbit like planets around an atomic nucleus. The laws of quantum mechanics make it namely impossible to determine where an electron is located at a given time. The position of an electron must rather be viewed as cloud of variable density: the denser the cloud, the highest is the probability to find the electron there. The electron has a spin (a kind of angular momentum) of value 1/2 and an electric charge of -1. The electron cannot be fragmented; it is not made up of something smaller.