SQLite is an embedded SQL database that does not require a separate server process. It is self-contained, transactional, and zero-configuration. The library is small in size and can run in minimal memory and stack space. SQLite implements ACID-compliant transactions and supports SQL features like joins and views while being faster than client-server databases for many common operations. It is suggested for use in applications like gadgets, websites, and browsers due to its small size and ease of use.