Synonym is an alias for any Table, View, Snap-shot, Sequence, Procedure, Function or Package. Because synonym is simply an alias, it requires no storage other than its definition in the data dictionary.

Advantages of having synonyms -
Synonyms are often used for security and convienience.
for Example, they can do the following things.

• Mask the name and owner of an object.
  
• Provide location transparency for remote objects of a distributed database.
  
• Simplify SQL statements for database users.