Tarantool is an open-source, in-memory database that combines the speed of Redis with the durability and querying capabilities of a relational database. It stores data in RAM for nanosecond-level latency and offers embedded Lua scripting, ACID transactions, and both key-value and SQL interfaces. Tarantool's architecture is designed for real-time systems: fintech platforms needing sub-millisecond trade execution, gaming engines tracking millions of concurrent players, and real-time analytics requiring immediate consistency. Its Lua scripting server-side allows complex multi-step operations to complete atomically without network roundtrips.