Redis is easy to understand and use

Advantages of redis
1. Data is stored in memory 2.
Redis can copy data to any number of slaves.
Redis uses
1. Installation There are many installation tutorials for redis on the
Internet , usually installed on Linux systems
2. Connection through java jedis redis

        Jedis jedis=new Jedis("192.168.174.129",6379,30000);
        jedis.set("name", "1");

Question:
What is the role of redis in practice?
Should redis data be synchronized to the database?