The database itself is a large platform and we have covered those parts that are relevant to our Spring and Android projects and contents. In this chapter, we have learned what the database is, as well as looking at the various types of it. We have seen a brief description of the DBMs. After that, we have learned about the JDBC, which is an API specification for connecting and moving data from frontend to backend. Then we have developed a project using JDBC where we created, read, updated, and deleted data from the databases. After this topic, we have learned another API called JPA, which is an approach to ORM and a system that maps Java objects to database tables and vice-versa. Then we have learned more about the JPA and its use with the help of a project. There, we have also learned about CRUD-based REST API. Lastly, we have learned about the latest technology of Android called architecture components. Also, we looked at one of the components called Room, which is a wrap of the top level of the SQLite database. Finally, I want to reiterate that this database chapter has not explained everything. If you want to learn more about the database, you can read our recommended books, and we have mentioned the links with the names of the books and authors under the Further reading section. In the next chapter, you can learn about the concurrency, which means the ability of different units of a program, algorithm, or problem.