Offline Password Cracking is an attempt to recover one or more passwords from a password storage file that has been recovered from a target system. Typically, this would be the Security Account Manager (SAM) file on Windows, or the /etc/shadow file on Linux. In most cases, Offline Password Cracking will require that an attacker has already attained administrator / root level privileges on the system to get to the storage mechanism.
As cybersecurity professionals we know a “strong” password is, supposedly, one that is at least 8 characters long with a combination of upper case, lower case, numbers, and special characters. But, as Bob Dylan said, the times they are a-changing. There is new movement in the industry to move away from this traditional password guidance to something more secure, user-centric, and friendly.
Online password cracking has advantages and disadvantages. It is effective if executed properly. There are numerous defenses to prevent attackers from cracking your passwords.
Most of us are brainwashed about what constitutes a secure or "strong" password. We often think a password that consists of 8 characters with complexity requirements (uppercase, lowercase, number, special character) is more secure than a "passphase" with no complexity requirements. This is not true.