What is the definition of data inconsistency?

Data inconsistency is one of the problem that occurs in the database..Data inconsistency means various copies of the data no longer agree..

(inconsistency- unchanging)

example:-

If a student want to make change in his records, the changes must be made in each and every pages that needs changes..

ex:- if a student changes his address, the new address must be changed in all applications in the institution that require address. The changes doesn't occur automatically in all pages when it is made in one page.