Archived code is preserved older website or application code, such as source files, backups, or legacy builds kept for reference. In security work, it matters because old code can still expose routes, parameters, and logic that are no longer visible in the current interface but may remain reachable on a server.
Attackers use archived code during reconnaissance to map an application, find forgotten endpoints, or identify unauthenticated handlers and weak assumptions left behind after a redesign. Defenders use the same material to compare old and live versions, spot stale APIs, and confirm that obsolete paths are truly disabled. Because archived code can reveal how a system used to work, it should be treated as sensitive until it has been reviewed, access-controlled, and retired.