PL/pgSQL is the default language used in PostgreSQL to implement runnable pieces of code. It can be used to implement functions, procedures, triggers, and so on. The language allows you to easily interact with the underlying database while providing foundations for iterations, conditionals, and exception handling, or, in short, all the features of a standalone programming language.
Thanks to the DO statement, it is possible to test and run a piece of code as an anonymous block of code. In the next chapters, we will learn how to use the language to implement reusable pieces of code such as functions and procedures.