[Data Structures] Retroactive Data Structures, originally introduced by Prof. Erik Demaine, is a paradigm which can be used to store information about the development of a data structure so that we could easily perform any operation on the host data structure at any point of time. We designed algorithms and data structures for Fully Retroactive BST, Hash and Union-Sameset, and studied existing retroactive data structures for Queue, Deque, Priority Queue and Union-find. It also includes our publication around our work.