A standard Binary Search Tree (BST) can degrade into a linked list, making operations O(N). Balanced trees ensure that this never happens, keeping the tree height at log N.
AVL Trees: Strict Balance
AVL trees use rotations to ensure the height difference between child subtrees is never more than one. This makes them great for read-heavy workloads where fast lookups are crucial.
Red-Black Trees: Performance over Precision
Red-Black trees allow for slightly less perfect balance than AVL trees, but they require fewer rotations during insertions and deletions, making them faster for write-intensive tasks.
Self-Balancing Logic
The core concept is that every operation that modifies the tree also checks for balance. If the tree becomes lopsided, a sequence of re-coloring and rotations restores the logarithmic height.