Indroduction to PL/SQL

The quick answer is from the PL/SQL User Guide:

PL/SQL, Oracle's procedural extension of SQL, is an advanced fourth-generation programming language (4GL). It offers software-engineering features such as data encapsulation, overloading, collection types, exceptions, and information hiding. PL/SQL also supports rapid prototyping and development through tight integration with SQL and the Oracle database.

But what does that mean? The key here are the words: procedural extension of SQL. PL/SQL is a procedural language like C++, Java, ADA, etc. If has variables and variable declarations, conditional controls like IF and CASE. It has looping structures such as LOOP, FOR LOOP and the WHILE LOOP. PL/SQL uses SQL to use, manipulate and save data to the database.

If I wanted to create my own, very short, definition of PL/SQL it would be this: PL/SQL is the Oracle native programming language that provides database-centric application development. It can natively call static SQL and provides multiple methods of calling dynamic SQL.

Example PL/SQL:
BEGIN
  -- A PL/SQL cursor
  FOR c1 IN (
    SELECT * FROM whatever ) -- This is SQL called by PL/SQL
  LOOP
 
    DBMS_OUTPUT.PUT_LINE( 'Column1 is: ' || TO_CHAR(c1.column1) ||
                          ', Column2 is: ' || c1.column2 ||
                          ', Column3 is: ' || TO_CHAR(c1.column3 ) );
  END LOOP;
 
END;