Yarn (Yet Another Resource Negotiator) is a resource-management platform responsible for managing computing resources in clusters and using them for scheduling users' applications. Part of the Apache Hadoop ecosystem, Yarn separates resource management and job scheduling into distinct components, allowing for more flexible and efficient handling of cluster resources. Yarn enables multiple data processing engines, such as MapReduce, Spark, and others, to run on the same cluster, optimizing resource utilization and improving performance.