lru-cache is a popular JavaScript package implementing a Least Recently Used (LRU) cache. It's designed for efficient storage and retrieval of data, optimizing performance by discarding the least recently accessed items when the cache reaches its capacity. Offering customizable options for cache size, expiration, and deletion behavior, lru-cache helps reduce latency and improve application responsiveness by caching frequently used data. It supports various data structures and is widely used in Node.js and browsers.