What does it mean for passwords to have complexity?

Passwords with complexity are designed to enhance security by being difficult to guess through brute-force attacks or common password cracking techniques. A complex password typically includes a combination of uppercase letters, lowercase letters, numbers, and special characters. This variety makes it significantly harder for unauthorized users to predict or uncover the password.

The requirement for complexity serves as a first line of defense against various cyber threats and plays an essential role in protecting sensitive information. Using a mix of characters increases the number of possible combinations, thereby making it substantially more challenging for attackers to gain access through guessing or automated tools.

The other options, while sometimes relevant to password policies, do not specifically address the idea of complexity. Changing passwords every 30 days may be a best practice but does not contribute to the complexity of a password itself. Limiting passwords to only uppercase letters would reduce complexity, and stating that passwords should be admin-controlled does not directly correlate with the concept of password complexity.