What does the term “password complexity” refer to?

The term “password complexity” primarily refers to the characteristics that make a password difficult to guess or crack. This includes aspects such as the length of the password and its unpredictability, meaning it should incorporate a mix of upper and lower case letters, numbers, and special characters. A complex password typically has enough variability and length that it significantly enhances security, making it more resilient against various attack methods like brute force or dictionary attacks.

The other options touch on related concepts but do not encompass the full meaning of password complexity. For example, while the number of characters in a password is a factor contributing to its complexity, it does not alone define it—complexity also involves the unpredictability and variety within the characters. Historical usage of previous passwords and methods of password storage are relevant to password management and security policies but do not directly relate to the specific notion of complexity.