Password Entropy
Entropy measures the unpredictability of a password, expressed in bits. A password with N possible characters and length L has entropy = L × log₂(N). Higher entropy means exponentially more combinations an attacker must try.
8-char lowercase: 8 × log₂(26) ≈ 37.6 bits12-char mixed: 12 × log₂(94) ≈ 78.7 bits