This section will introduce Redis and how to use Spring Data Redis repositories to provide Create, Retrieve, Update, Delete (CRUD) operations on Redis easily, and also how to use the reactive capabilities of Spring Data with Redis. The decision to use Redis was made because the data in a Taxi domain is highly volatile and tends to change very often (such as the location of a moving Taxi), and also because of its out-of-the-box Geo data support. This is because Redis holds in memory most of the time; it suits well for this.