In this contribution we present an overview on the relation between the complex structure of ionic liquids (ILs) and its impact in the field of surface science. The results herein described result mainly from modeling and simulation work carried out at Centro de Química Estrutural, Universidade de Lisboa, complemented in some cases by experimental results obtained at Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa or elsewhere. The overview starts with the description of nano-segregation and self-aggregation phenomena experienced by pure ionic liquids in bulk phases (bi-continuous structures in the isotropic liquid or the formation of liquid-crystal phases). This is followed by the analysis of IL self-aggregation in molecular solvent solutions (micelle or gel formation). The second part of the overview is devoted to the study of the structuration of ILs at the IL/vacuum, IL/liquid or IL/solid interfaces. The final part deals with thin IL films stabilized between air/solid, air/liquid or solid/solid boundaries.