When you build real-world applications, you might need to persist your application data into persistent storage. You can define the data model of your application using various Go types, especially structs. In most use cases, you might need to persist your application data into databases. This chapter shows you how to persist application data into databases such as MongoDB, RethinkDB, InfluxDB, and PostgreSQL. MongoDB is a popular NoSQL database that is widely used for many modern applications. RethinkDB is another NoSQL database that comes with real-time capabilities that allow you to build real-time web applications. Time series databases are becoming the next big thing in data management technologies, and hence this chapter includes recipes for working with InfluxDB, a popular time series database written in Go. This chapter also provides recipes for working with traditional SQL databases.