The aim of this chapter is threefold. First, to avoid unnecessary confusion, I introduce some terms that are used repeatedly throughout this book. The most important include selectivity and cardinality, cursor, soft and hard parses, bind variable peeking , and adaptive cursor sharing. Second, I describe the life cycle of SQL statements. In other words, I describe the operations carried out in order to execute SQL statements. During this discussion, special attention is given to parsing. And third, I describe how to instrument application code and database calls.