Credential stuffing is a type of cyber attack where hackers use stolen usernames and passwords to gain unauthorized access to user accounts on various websites. This method takes advantage of the fact that many people reuse the same login credentials across multiple platforms, making it easier for attackers to breach accounts. Once attackers successfully log in, they can steal personal information, make unauthorized purchases, or even sell access to the accounts. To protect against credential stuffing, users should create unique passwords for each account and enable two-factor authentication whenever possible, which adds an extra layer of security.