Introduction to a Virtual Special Issue on plant volatilesChemistry is crucial in mediating all types of antagonistic, mutualistic and neutral ecological interactions between all kinds of organisms and on all organizational levels, from the intra-cellular over the organismal to the ecosystem level (Raguso et al., 2015). Plant life seems particularly dependent on chemical information, a fact directly linked to one of the most cited questions in biology: Why are there so many different kinds of plant secondary metabolites? The last decades have seen various exciting approaches to answer this question from a proximate (e.g. physiological, developmental) and ultimate (e.g. functional and evolutionary) perspective, and plants were increasingly used as the basic model systems to understand chemical information transfer. Thereby the study of low molecular weight, lipophilic compounds emitted into the headspace surrounding the plant, so-called volatile organic compounds (VOCs) (Pichersky et al., 2006), generated especially valuable new concepts that, among other things, re-introduced the application of behavioral biology principles into the functional analysis of plant traits (Karban, 2008).Today > 1700 VOCs from at least 90 plant families have been identified (Knudsen et al., 2006) and, in part, are known to play roles in plant signal transduction, meditate interactions between plants, including recognizing kin, and provide host-specific information to antagonists (e.g. pathogens and herbivores) as well as mutualists (e.g. pollinators, seed dispersers, natural enemies of antagonists) (Dudareva et al., 2013;Heil, 2014). New Phytologist, with its strong focus on plant organismal interactions has become a natural facilitator of research into plant VOCs, both through direct funding contributed to the leading conferences in the field and as a highimpact venue for publishing new research on all aspects of plant VOC production. This Virtual Special Issue celebrates these contributions by featuring publications that are chronologically enveloped by two New Phytologist-sponsored Gordon Research Conferences on 'Plant Volatiles' (Ventura, California in 2014 and2016). The featured publications roughly reflect the research and syntheses over the related time period (2012)(2013)(2014)(2015) and includes studies into the mechanisms of biosynthesis and physiology, as well as the ecological functions of plant VOCs in mediating plant interactions with other plants, pollinators, herbivores and natural enemies of herbivores as well as larger scale ecosystem effects. Four reviews (