Bulk Binds

The assigning of values to PL/SQL variables in SQL statements is called binding. The binding of an entire collection at once is called bulk binding. Bulk binds improve performance by minimizing the number of context switches between the PL/SQL and SQL engines. With bulk binds, entire collections, not just individual elements, are passed back and forth.
The keyword FORALL instructs the PL/SQL engine to bulk-bind input collections before sending them to the SQL engine. Although the FORALL statement contains an iteration scheme, it is not a FOR loop. In a FORALL statement, if any execution of the SQL statement raises an unhandled exception, all database changes made during previous executions are rolled back. However, if a raised exception is caught and handled, changes are rolled back to an implicit savepoint marked before each execution of the SQL statement. Changes made during previous executions are not rolled back.
The following restrictions apply to the FORALL statement:
You can use the FORALL statement only in server-side programs (not in client-side programs). Otherwise, you get the error this feature is not supported in client-side programs.
The INSERT, UPDATE, or DELETE statement must reference at least one collection
The keywords BULK COLLECT tell the SQL engine to bulk-bind output collections before returning them to the PL/SQL engine. You can use these keywords in the SELECT INTO, FETCH INTO, and RETURNING INTO clauses.

The FORALL statement is specifically used for processing DML (INSERT, DELETE, and UPDATE) statements to improve performance by reducing the overhead of SQL processing. The PL/SQL interpreter executes all procedural statements. However, all SQL statements in the PL/SQL block are sent to the SQL engine, which parses and executes them. The PL/SQL-to-SQL context switch adds some overhead, which could become significant when SQL statements are nested in loops. For instance, if it's repeated in a loop—say, 1,000,000 times—that could slow down code execution substantially.
The FORALL statement has a structure similar to FOR LOOP with a range. However, it doesn't contain an END LOOP statement and it cannot contain any statements other than the index, lower and upper bound, and actual SQL statement (which refers to the index). The range specified by lower and upper bounds (in my example, it's 1 to 10,000) must be contiguous and all the elements within that range must exist, otherwise an ORA-22160 exception will be raised.
The FORALL clause is used for DML statements. The equivalent statement for a bulk fetch is the BULK COLLECT clause, which can be used as a part of SELECT INTO, FETCH INTO, or RETURNING INTO clauses
The BULK COLLECT clause can be used for both explicit (FETCH INTO) and implicit (SELECT INTO) cursors. It fetches the data into the collection (PL/SQL table, varray) starting with element 1 and overwrites all consequent elements until it retrieves all the rows. If the collection is varray, it has to be declared large enough to accommodate all fetched rows, otherwise an ORA-22160 exception will be raised.
The bulk binds features allow users to increase the performance and reduce the overhead of SQL processing by operating on multiple rows in a single DML statement. The entire collection-not just one collection element at a time-is passed back and forth between the PL/SQL and SQL engines. According to Oracle, during internal benchmark tests there was a 30 percent performance improvement as a result of using these new features.