Authentication events are records created when a user, service, or device attempts to prove its identity and gain access. They usually include logins, failed password checks, multi-factor authentication prompts, token use, session creation, and account lockouts. Security teams rely on these records because they show who tried to access what, from where, and when.
In cyber security, authentication events help defenders spot brute-force attacks, credential stuffing, impossible travel, unusual new devices, and suspicious remote access. They are especially useful during ransomware investigations, where attackers often abuse stolen credentials before encrypting systems or stealing data. Reviewing authentication logs can confirm whether a claimed incident involved real account abuse, or whether the activity was normal. They are a key source of evidence, but they should be checked alongside file, endpoint, and network logs for a full picture.