In a package registry, a release is a published version of software that users and automated systems can download, install, and depend on. It is more than a file upload: a release signals that a specific version is available and should be treated as a stable point in the software supply chain.
Releases matter in cyber security because downstream tools often trust them as fixed artifacts. If an attacker gains publishing credentials or compromises a CI/CD pipeline, changing an older release can poison dependencies without obvious warning. Defenses therefore focus on protecting release integrity with signing, access controls, review checks, and policies that limit late edits. Some registries also restrict changes to older releases so that time itself becomes part of the trust model.