YugabyteDB is composed of nodes that form a universe, which can be physical machines, virtual machines, or containers. A universe is made up of one or more clusters, with each cluster containing a primary cluster and optional read replica clusters. Clusters can be deployed in various configurations, including single availability zones, multiple AZs within a region, or across multiple regions and cloud providers. YugabyteDB uses two servers: YB-TServer, which handles I/O operations and replicates data, and YB-Master, which maintains system metadata and performs administrative tasks using Raft. Data is stored as tables in logical keyspaces, which are grouped into universes and can span clusters. The universe automatically shards, replicates, and rebalances table data across the cluster.