What is the primary characteristic of a binary search algorithm?

The primary characteristic of a binary search algorithm is that it only works with sorted data. This algorithm takes advantage of the order of elements in a list. By repeatedly dividing the search interval in half, binary search efficiently narrows down the potential location of the target value. If the target value is less than the middle element of the list, the search continues in the left half, and if it is greater, it continues in the right half. This systematic halving allows binary search to achieve a time complexity of O(log n), making it significantly faster than linear search methods for large datasets.

The requirement for sorted data is crucial because the algorithm relies on the ability to eliminate half of the search space at each step based on comparisons to the middle element. Without sorted data, the logic used in binary search would not hold true, leading to incorrect results. Therefore, understanding that binary search operates on sorted data is fundamental to grasping how and why it functions effectively.