Nanowires are tiny filamentous structures that are 1000 times thinner than a human hair. Because of their small thickness, electrons can freely travel along the wire. Their motion in the other two directions however is governed by quantum mechanics. As a result, nanowires have extraordinary properties that are exploited in a number of technologies, such as magnetic storage devices, solar cells, electrocatalysts, and electronics. These potent fibers are produced either by extraction from a bigger piece of material, or by electrochemial growth in templates, such as nanoporous aluminum oxide. During growth, the nanostructures assume certain physical properties, like strain, which influence their performance. Now researchers have observed in situ how these properties develop during nanowire growth.