In 1996 Lov Grover, at Bell Labs, presents at STOC a quantum algorithm searching an unstructured database of N elements in O(√N) operations versus O(N) classically — a quadratic, provably optimal speedup for unstructured search. Its amplitude-amplification mechanism has direct implications for symmetric cryptography, halving the effective bit-security of algorithms like AES and motivating doubled key lengths in post-quantum standards.