WordPress profile pages contain a visual indicator which shows the strength of a user’s chosen password. This is nice, but WordPress doesn’t actually enforce this in any way, so users are free to select weak passwords.
Minimum Password Strength uses the same method to calculate a password’s strength, but forces users to meet a minimum strength requirement before they can change their password.
By default, passwords must have “Medium” strength, but administrators can change this to force passwords to be at least “Weak”, “Medium”, or “Strong”. To change the minimum strength, go to Settings -> Password Strength after installing Minimum Password Strength.
For now, all users have the same password strength requirements, but a later release will allow administrators to select different strength requirements for different roles.