Account takeover (ATO) attacks are a growing cybersecurity threat where malicious actors gain unauthorized access to user accounts, often causing significant financial harm to both users and businesses. These attacks typically occur through phishing or exploiting weak credentials, leading to unauthorized transactions and compromised personal data. Traditional security measures are increasingly inadequate against sophisticated online fraud, prompting the need for advanced solutions like Fingerprint, a device intelligence platform. Fingerprint enhances security by generating unique visitor identifiers using device attributes, allowing businesses to detect anomalies and suspicious activities such as VPN usage or bot behavior. By integrating Fingerprint, businesses can recognize returning users, prevent fraud, and maintain a secure and seamless user experience. This guide details the planning, implementation, and best practices for using Fingerprint to safeguard accounts against takeovers, emphasizing the importance of understanding user behavior, setting thresholds for suspicious activities, and ensuring compliance with regulations like GDPR.