User identification is a critical component of online security, allowing systems to confirm a user's identity and protect personal information from unauthorized access, thus preventing fraud and abuse. While traditional methods such as username and password are common, they are increasingly vulnerable to attacks like phishing and credential stuffing, prompting a shift towards more secure approaches such as multi-factor authentication (MFA) and single sign-on (SSO). These methods enhance security by requiring multiple forms of verification, such as something you know, have, or are (e.g., passwords, physical tokens, or biometrics). Device identification, through technologies like browser fingerprinting, offers an additional layer of security by accurately verifying users based on their devices without requiring visible steps from users. Businesses are encouraged to adopt a mix of these strategies to ensure robust protection against unauthorized access, balancing security with user experience, and complying with security standards such as SOC 2.