In competitive programming, using the right data structure can make a significant difference in the performance of your solution. Arrays and hash maps (dictionaries) are the most common and provide fast lookups and updates. For more complex problems, data structures like heaps (priority queues) are useful for managing dynamic sets of data, especially in problems involving sorting or searching. Segment trees and binary indexed trees (BIT) are ideal for problems involving range queries and updates. Understanding when and how to use these data structures is key to solving problems efficiently. The choice of data structure often depends on the type of operations required and the size of the input.