The growing penetration of distributed energy resources (DER) is challenging traditional approaches to electricity pricing, planning, and operation. This chapter introduces and discusses locational marginal value (LMV) metrics as practical tools for improving economic efficiency under these new conditions. The novelty lies in providing power sector practitioners with a simplified framework for when and how to increase granularity of existing procedures, as well as a pragmatic mathematical method for estimating and applying LMV in real-world contexts. Section 1 establishes the rationale for LMV by clarifying terminology and introducing the context of growing debates on tariff reform in systems with high DER shares. We argue that recent proposals to move from uniform national electricity tariffs to zonal or nodal price setting and congestion management exemplify a broader shift toward higher-resolution modeling, planning, trading, and dispatch: developments that mirror the inherent granularity of DER. Understanding the technical and economic implications of this shift is essential for practitioners tasked with integrating growing shares of DER into power systems. Section 2 equips practitioners with a simplified yet readily applicable mathematical basis for calculating present and future LMV. The approach is designed to be comprehensive enough for meaningful application, aiming for a more widespread application in industry settings and international working groups such as CIGRE. Section 3 provides illustrative real-life case studies that showcase typical challenges and solutions related to nodal and zonal valuation of DER. These examples, drawn from recent practical applications across the globe, demonstrate how LMV metrics can inform decision-making and support more efficient, resilient, and cost-reflective power sector practices.