Energy storage technologies can provide services to the electricity grid that are necessary for its usability, stability, and reliability. The services, such as power factor correction and renewable energy arbitrage, are defined by duration, cycling occurrence, power, and market price. Storage technologies suitable to these applications, such as pumped hydro and batteries, are defined by their usable energy, power, efficiency, operating range, availability, lifetime, and cost. In this article, grid services and storage technologies are examined using a range of metrics. Through a series of figures and discussions, the reader is provided with a method for comparing universal characteristics with regional/technology specific values. This provides a guiding strategy to help identify overlap between service needs and storage technology capabilities, so as to aid in the specification and selection of systems for present and future grid storage opportunities.