This document provides an introduction to data structures and algorithms. It defines an algorithm as a set of steps to solve a problem and describes data structures as organized ways to store and access data. Common data structures include arrays, stacks, queues, linked lists, trees and graphs. Abstract data types define the fundamental operations on data objects in a data structure independently of their implementation. Linear data structures like arrays represent lists in one dimension while non-linear structures represent two-dimensional relationships. Stacks follow the last-in, first-out principle with push and pop operations, while queues are first-in, first-out. Selection of the appropriate data structure depends on the application.