Binary search is an efficient algorithm used to find a specific value in a sorted list. It works by repeatedly dividing the search interval in half. If the target value is less than the middle element, the search continues in the lower half; if it's greater, the search continues in the upper half. This process is repeated until the value is found or the interval is empty. This method is much faster than a linear search, especially for large datasets, as it reduces the number of comparisons needed. The time complexity of binary search is O(log n), making it a preferred choice for searching in sorted arrays.