What is redundancy? What problems are associated with redundancy?

Redundancy is the mechanism that occurs in database's data as the same data is stores in the multiple location. It creates repeated data by accident or for backup purpose.

The issues that arise due to the redundancy of the data is the storage space in database gets consumed and thus wastes the space in storing information in multiple locations. When any update occurs in the stored data's field value, it also has to be changed in the multiples occurrences.