Redis stores data in cache. You can set how long the data should be cached. When an object has expired, the application has to retrieve the data again from the database or recompute them before they are returned to Redis. This avoids serving expired data for too long. Redis is a "distributed key-value store": data are stored as plain text or one of the other supported data types. These data are identified by a unique key. The data are not stored locally but are distributed.