This meeting follows on from Faraday Discussion 154 held in 2011 and discusses a range of topics, such as ionicity, structure, electrochemistry, phase behaviour, and introduce areas which were only emerging at that point, such as interactions with liquid and solid interfaces. Ionic liquids have been the focus of intense research over the last 20 years because of their remarkable potential for applications coupled to favourable environmental properties. Ionic liquids are also a medium whereby the nature of the complex interactions (Coulombic, van der Waals and hydrogen bonding) provides a liquid whose structure and properties can be tuned by the choice of the cation and anion wherein reactions are likely to be distinct in terms of activity and selectivity profiles compared with common molecular solvents.