What Are The Advantages Of De Normalized Data?

As denormalized means the data with duplicacy means same named is entered twice /thrice or even more, its just the opposite of normalized
As per your question the main advantage of denormalized data is that if we have thousands of records then it require time to move on particular record so to avoid this database programmer add some duplicate data to existing data records(tables) so that he can easily find it

more precisely just to save the time to access the data

Thanks
Sachin