Computational Social Science is an interdisciplinary field closely related to complex systems as well. CSS is largely aiming to bring computational and data-driven methods to understand social phenomena, particularly in those cases where traditional mathematical and econometric methods have failed. Unlike natural sciences (biology, chemistry, physics, etc.), social sciences have less access to laboratory experiments (you cannot put the whole world in a lab), altghough experiments and experimental studies with human subjects have been done and are being done still. But the easiest and most efficient way to understand social phenomena now is to use computer simulations.