Mesos allows clusters of nodes to be treated as one big computer by sharing computational resources like cores, memory, and disks. It is a top-level Apache project that acts as a cluster resource negotiator, scaling to 10,000s of nodes in a fault-tolerant manner. Mesos supports running Docker containers at scale through frameworks like Marathon and Chronos, which provide interfaces for launching long-running and batch/one-off services respectively. Twitter uses Mesos as the "cornerstone" of their elastic compute infrastructure to build new services and scale to millions of daily users.