Altmetrics, or alternative metrics, are forging a new way to capture the impact of not only articles, but also scholarly or research "products" by tracking them when they are mentioned online, such as in blogs or social media platforms. While altmetrics have a lot of potential, there are also some limitations preventing their full acceptance alongside traditional citation metrics. This column will explain the basics of altmetrics and altmetric tools, discuss some of the ways they can be used in libraries, and explore some possible concerns with this new metric. A list of resources for additional information is also included.