Cassandra is a decentralized structured storage system designed for high availability, high write throughput, and failure tolerance. It uses a gossip-based protocol for node communication and a ring topology for data partitioning across nodes. Data is replicated across multiple nodes for fault tolerance. Cassandra provides low-latency reads and high-throughput writes through its use of commit logs, memtables, and Bloom filters. It was developed at Facebook to power user messaging search and scaled to support over 50TB of user data distributed across 150 nodes. Benchmark results show Cassandra providing lower read and write latencies compared to MySQL on large datasets.