How does bubble sort work and what is its complexity?

Bubble sort repeatedly steps through the array, comparing adjacent elements and swapping them if they're in wrong order. The largest elements 'bubble' to the end in each pass. Time complexity is O(n^2) in average and worst case (already sorted in reverse), O(n) in best case (already sorted with optimization flag). Space is O(1). Simple but inefficient for large datasets; mainly used for educational purposes.