25H2 is a Windows 11 feature update designation. In Microsoft naming, the first two digits point to the release year and the H2 tag indicates the second half of the year. In practice, it identifies a specific Windows feature-update branch or targeted release wave that devices can be configured to receive.
For security teams, version designations like 25H2 matter because compatibility, policy behavior, and patch timing can change between releases. Defenders use them to plan testing rings, validate drivers and security tools, and control rollout before broad deployment. Attackers also care about them: many exploits depend on the exact Windows build or feature set, and delayed upgrades can leave older versions exposed to known weaknesses. Treating 25H2 as a deployment target, not just a label, helps keep patching and hardening aligned.