What is the load factor in a hash table and why is it important?

Load factor is the ratio of number of entries to the number of buckets (n/capacity). It measures how full the hash table is. A higher load factor means more collisions and slower operations; typical threshold is 0.75. When exceeded, the table is resized (usually doubled) and all elements are rehashed. Balancing load factor is crucial: too low wastes memory, too high degrades performance from O(1) toward O(n).