This document provides an introduction to data structures. It defines data and structures, and explains that data structures provide organized ways to store and retrieve data. The document then covers several common linear data structures like arrays, stacks, queues, and linked lists. It describes each structure's properties and common operations. The document also discusses non-linear data structures like trees and graphs, their representations and operations. Finally, it provides guidance on selecting the appropriate data structure based on a problem's resource constraints and required operations.