An email alias is an alternate address that forwards messages to a primary mailbox. It lets one person use different addresses for shopping, newsletters, work sign-ups, or password recovery without exposing the main account address everywhere. Some aliases are simple forwarding addresses, while others are generated per service and can be disabled individually.
In cyber security, aliases reduce the attack surface around identity and login recovery. If a public site is breached, attackers may learn only the alias, not the primary address used for important accounts. That can also make phishing and credential-stuffing campaigns less effective because the real inbox is harder to target directly. Defensively, aliases help users track which service leaked or sold an address, and they make it easier to retire a compromised alias without changing the main mailbox. They are not a complete defense: if an attacker already has the password or a session token, an alias alone will not stop account takeover. Used with unique passwords and 2FA, however, aliases are a practical privacy and resilience layer.