Nature Reviews Materials aims to cover the making, measuring, modelling and manufacturing of materials - thus, looking at materials science throughout the pipeline of laboratory discovery to functional device. Nature Reviews Materials is an online-only journal for the weekly publication of Reviews, Perspectives and Comments in all scientific disciplines within materials science. Our Reviews aim to be balanced and objective analyses of the selected topic - with descriptions of relevant scientific literature and discussions that are easy to grasp for recent graduates in any materials-science related discipline, as well as informing principal investigators and industry-based research scientists of the latest advances. Reviews should provide the authors' insight into future directions and their opinion of the major challenges faced by researchers in the field. Perspectives - as the name suggests - take a look at a topic from a slightly different perspective. They may offer more personal viewpoints, explain the historical background to a topic, or discuss some of the social, ethical or environmental factors related to materials science research in academia and industry.