i. Data distribution: It is a type of data storage. Data can be either replicated(centralized) or Fragmented (distributed). Distributed scenario is classifies as horizontal partitioning or vertical partitioning. Horizontal partitioning means records are partitioned without partitioning of attributes in various databases while vertical partitioning is attribute wise data are partitioned in various databases. ii. Data modification: Data modification means changing of original database to some secure form so that it remains protected and information is not leaked to other. Different methods for data modification are perturbation, blocking, swapping and sampling.