In this talk I will give a brief overview of three projects which explore different facets of electron interactions in mesoscopic systems. I will start from the discussion of magnetic materials where microscopic spin-orbit interactions - a relativistic correction to electron spectrum which connects spin and orbital degree of freedom - allow us to control macroscopic properties, such as magnetization direction. In high mobility 2D electron gases subject to high magnetic fields interaction effects lead to the formation of a variety of correlated states, such as fractional quantum Hall effects, Wigner crystal and, possibly, states with non-Abelian excitations. I will report our recent discovery of a new type of topological excitation forming a new state of matter in two-dimensional electron systems. The system enables control of the density of topological excitations with different symmetry and investigation of previously unexplored regime of thermodynamic phase transitions. As a third example, I will discuss how a combination of low dimensionality, strong spin-orbit interaction and superconducting coupling leads to the formation of an entirely new state of matter which supports excitations with non-Abelian statistics. These exotic excitations have properties of particles proposed by E. Majorana almost 80 years ago, and evidence of their existence have been clearly seen in our experiments. Finally, I will show how research ideas explored in these three topics lead to the development of new materials which may be the key for the development of topologically protected fault-tolerant quantum computers.