I have gone through the definition on http://en.wikipedia.org/wiki/Database_engine several times:
A database engine (or "storage engine") is the underlying software component that a database management system (DBMS) uses to create, read, update and delete (CRUD) data from a database.
What I do not understand is what is left to do, isn't CRUD all that the databases do?
If the database engine performs these functions, what does the rest of the database do?