PL/SQL stands for Procedural Language for SQL, and it is Oracle Corporations procedural extension for SQL and the Oracle relational database. PL/SQL is a block-structured language that enables developers to combine the power of SQL with procedural statements. It includes procedural language elements such as conditions and loops, and can handle exceptions (run-time errors). It allows declaration of constants and variables, procedures, functions, packages, types and variables of those types, and triggers. PL/SQL is designed to compute and return a single scalar value or a single collection, such as a nested table or VARRAY. PL/SQL is available in Oracle Database, Times Ten in-memory database, and IBM Db2.

PL/SQL is a powerful, yet straightforward database programming language. It is easy to both write and read, and comes packed with lots of out-of-the-box optimizations and security features. PL/SQL program units are compiled by the Oracle Database server and stored inside the database, and at run-time, both PL/SQL and SQL run within the same server process, bringing optimal efficiency. PL/SQL automatically inherits the robustness, security, and portability of the Oracle Database.

PL/SQL is compatible with SQL, and because of this tight integration of the two programs, PL/SQL enables users to utilize all SQL data manipulation, cursor control, transaction statements, and all other SQL functions, operators, and pseudo-columns. Users arent required to convert between PL/SQL and SQL data types. Additionally, PL/SQL supports both static and dynamic SQL.

In summary, PL/SQL is a procedural language designed specifically to embrace SQL statements within its syntax, and it is used to extend the functionality of SQL for developers working with Oracle databases.