MERGE statement in SQL Server

What is MERGE (Transact-SQL) ?
Understanding the SQL MERGE statement
Syntax
MERGE target_table USING source_table
ON merge_condition
WHEN MATCHED
THEN update_statement
WHEN NOT MATCHED
THEN insert_statement
WHEN NOT MATCHED BY SOURCE
THEN DELETE;

Note:The MERGE SQL statement requires a semicolon (;) as a statement terminator