Part 3/19:
A central focus of the talk is on cryptographic hash functions, especially SHA-256. The speaker clarifies how hash functions work: they take any data input, produce a fixed-length fingerprint (or hash), and behave deterministically—meaning the same input yields the same output every time, but small changes in input produce drastically different hashes. This cascade effect underpins many blockchain operations, such as verifying document integrity or software authenticity.