Without doubt, one of the most fascinating questions ever asked is ''What is life?'', immediately followed by ''How and where did life arise?''. Both questions are by no means exclusively related to chemistry and biology. Indeed, it was soon realized that concepts from astrophysics, geochemistry, geophysics, planetology, earth science, bioinformatics, complexity theory, mathematics and many more are needed to figure out sensible answers. This themed issue focuses on a specific and very intriguing aspect of the problem, i.e. the evolutionary chemical steps that brought simple molecules towards a kind of self-organization, which ultimately gave rise to the first biopolymers and to proto-metabolism. This is a key point as today life is sustained by the intricate biochemistry occurring within extremely complex cells, which were obviously absent in the early days of prebiotic chemistry. Astrochemical evolution has been able to give rise only to very simple inorganic compounds according to current knowledge. Research on how life emerged on our primitive Earth from very simple inorganic compounds started in the 1950s with the famous Miller experiment and involves an interdisciplinary approach, which is well represented in this issue, and is by no means limited to chemistry, in complete agreement with D. Deamer's statement from his book ''First Life'' that ''life can emerge where physics and chemistry intersect''. The search for life's signature on other worlds, at least in our solar system, is described in three contributions, all devoted to clarifying the fascinating chemistry happening on Titan, the largest moon of Saturn. Raulin and co-workers (DOI: 10.1039/C2CS35014A) merge observations from the Cassini-Huygens mission with theoretical modeling and experimental simulations to provide a detailed view of the complexity of Titan's atmosphere, which is relevant as a model of the primitive upper terrestrial atmosphere. Kaiser and Mebel (DOI: 10.1039/ C2CS35068H) combine an experimental approach (crossed molecular beams reactions) with sophisticated quantum mechanical methods to describe the complex reaction pathways leading to the formation of polyacetylenes and cyanopolyacetylenes in Titan's aerosol layers. Balucani (DOI: 10.1039/C2CS35113G) uses the same combination of experimental and theoretical techniques to disentangle the intricate elementary reactions involving N atoms and hydrocarbons to bring about prebiotic N-containing molecules in Titan's