The formation and evolution of the heavy neutron-capture elements (Z > 37) are to date not well understood. Therefore, abundance and galactic chemical evolution (GCE) studies of these heavy elements may carry key information to this open question. Strontium (Sr) is one of the two heavy elements (Sr and Ba) that show intrinsically very strong absorption lines even in extremely metal-poor stars (and remains detectable at low spectral resolution). Hence, the 4077 Å Sr II line provides a unique insight into the behaviour of heavy neutron-capture elements at all metallicities and resolutions. Here the focus is on strontium, its 3D and NLTE (non-local thermodynamic equilibrium) corrections, as well as chemical evolution.