While research metrics may seem well established in the scholarly landscape, it can be challenging to understand how they should be used and how they are calculated. The Metrics Toolkit is an online evidence-based resource for researchers, librarians, evaluators, and administrators in their work to demonstrate or assess the impact of research.This article was selected by the Virtual Projects Advisory Committee of technology experts after an annual call for projects in MLA-FOCUS and announcements to encourage submissions from all types of libraries.