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  "description": "Redis (Remote Dictionary Server) is an in-memory data store that holds its dataset in RAM for sub-millisecond access. Beyond simple key-value, Redis supports rich data structures including strings, hashes, lists, sets, sorted sets, streams, bitmaps, and HyperLogLog.\n\n\nHow it works\n\nA Redis server accepts commands over a simple text protocol (RESP). Commands are executed single-threaded, which keeps semantics simple and operations on a single key atomic. Replication is asynchronous primary-replic",
  "path": "/engineering-glossary/redis-remote-dictionary-server/",
  "publishedAt": "2026-03-27T22:09:59.000Z",
  "site": "https://sahilkapoor.com",
  "tags": [
    "Caching",
    "Memcached",
    "Eviction Policy",
    "TTL",
    "Pub/Sub",
    "In-memory Database",
    "Valkey",
    "Redis Cluster",
    "Redis as Infrastructure: Caching, Coordination, and Scale"
  ],
  "textContent": "**Redis** (Remote Dictionary Server) is an in-memory data store that holds its dataset in RAM for sub-millisecond access. Beyond simple key-value, Redis supports rich data structures including strings, hashes, lists, sets, sorted sets, streams, bitmaps, and HyperLogLog.\n\n## How it works\n\nA Redis server accepts commands over a simple text protocol (RESP). Commands are executed single-threaded, which keeps semantics simple and operations on a single key atomic. Replication is asynchronous primary-replica by default; sharding is achieved via Redis Cluster, which partitions keys across nodes by hash slot. Persistence options include periodic RDB snapshots and an append-only file (AOF) with configurable flush policy.\n\n## Common use cases\n\n  * **Caching.** TTL-based eviction with millisecond reads.\n  * **Session store.** Centralized session state for horizontally scaled web applications.\n  * **Rate limiting.** Atomic increment with TTL backs token-bucket and sliding-window limiters.\n  * **Queues and streams.** Lists, sorted sets, and Streams cover work queues and log-style consumers with consumer groups.\n  * **Pub/Sub.** Lightweight fan-out messaging.\n  * **Leaderboards and counters.** Sorted sets and atomic counters support real-time leaderboards and analytics.\n\n\n\n## Origin\n\nCreated in 2009 by Salvatore Sanfilippo (antirez) and released under the BSD license. Redis Ltd. (formerly Redis Labs) stewards the project; the license was changed in 2024, which prompted forks including Valkey, backed by AWS and the Linux Foundation.\n\n🔗\n\n**Related Terms**\nCaching, Memcached, Eviction Policy, TTL, Pub/Sub, In-memory Database, Valkey, Redis Cluster\n\n📖\n\n**Further Reading**\nRedis as Infrastructure: Caching, Coordination, and Scale",
  "title": "Redis",
  "updatedAt": "2026-05-13T19:03:40.595Z"
}