Apache Mesos is an open-source cluster management system that simplifies the process of managing resources across a distributed system. It allows multiple applications to share the same pool of resources, such as CPU and memory, efficiently. By abstracting the underlying hardware, it enables developers to deploy and scale applications seamlessly. Designed for high scalability, Apache Mesos can manage thousands of nodes and run various workloads, including Hadoop, Spark, and containerized applications. Its architecture supports fault tolerance and resource isolation, making it a popular choice for organizations looking to optimize their infrastructure and improve application performance.