H2
H2 is an open-source, in-memory, embedded relational database management system written in Java. It is designed for fast performance and minimal configuration, supporting standard SQL and JDBC APIs, and can run in embedded, server, or mixed modes. It is commonly used for development, testing, and small-scale applications due to its lightweight nature and ease of setup.
Developers should learn H2 for rapid prototyping, unit testing, and development environments where a lightweight, self-contained database is needed without external dependencies. It is ideal for Java-based applications, Spring Boot projects, and scenarios requiring temporary or in-memory data storage, such as demos or proof-of-concepts, as it simplifies setup and reduces overhead compared to full-scale databases.