A strain gauge is a device used to measure the amount of deformation or strain in an object when it is subjected to stress. It typically consists of a thin wire or foil arranged in a grid pattern, which changes its electrical resistance when stretched or compressed. This change in resistance can be measured and converted into a strain value, allowing engineers to assess the structural integrity of materials and components. Strain gauges are commonly used in various applications, including civil engineering for monitoring bridges and buildings, as well as in aerospace to test aircraft components. They play a crucial role in ensuring safety and performance by providing real-time data on how materials respond to forces.