In the world of programming, data structures serve as the backbone for developing efficient algorithms. This section explores fundamental and advanced data structures, focusing on how they support and enhance algorithmic problem-solving. Understanding the right data structure to use is crucial for optimizing performance, memory usage, and code clarity.We begin with core structures such as arrays, linked lists, stacks, and queues, examining how they operate, where they are used, and their time and space complexities. Moving deeper, we cover hierarchical and non-linear structures like trees (binary trees, binary search trees, heaps, tries) and graphs (directed, undirected, weighted, unweighted), which play a critical role in solving complex real-world problems like searching, scheduling, and network modeling.Special attention is given to hash tables and sets, which provide near-constant time access and are essential for fast lookups and caching. Advanced data structures such as segment trees, Fenwick trees, disjoint sets, and suffix arrays are also introduced for readers interested in competitive programming and systems-level design.This section emphasizes the practical application of each structure with examples in common programming languages, illustrating how to implement, manipulate, and choose the most suitable data structure for a given problem.