A password is a sequence of characters used to verify a user's identity when accessing a computer system or online account. Choosing a secure password is difficult because passwords that are easy to remember are also easy for attackers to guess, yet complex passwords are hard for users to remember. Research shows that common passwords like names, dates, and favorite sports teams are insecure. Password cracking is used both maliciously to gain unauthorized access, and beneficially such as for users to recover forgotten passwords or for system administrators to check security. Creating strong passwords involves mixing letters, numbers, and symbols, avoiding personal information, and using a unique password for each important account.