Data deduplication refers to size reduction of data by eliminating data redundancy due to duplication. Possibility of duplication is high when size of data is huge. As the data especially digital data is growing drastically on the Internet due to emerging online ways of communication and interaction in various areas such as social media, banking, and marketing, the problem of duplicate data has become serious. There are various data deduplication techniques that can be used to reduce its size. Apart from reducing the required storage space this reduction may result into different adjoining benefits. For example, it saves device cost and time required for backup and archive when data is to be stored on secondary storage. In case of primary storage, it eliminates duplicate disk I/Os and thus reduce the time of program execution. When data is meant for cloud storage, deduplication reduces time for data uploading on WAN. When data is to be stored on virtual machine, it saves time for its migration. When data is on network, its size reduction reduces time of transmission and reduces redundancy for WAN optimization.