Armor is a protective material or structure designed to reduce the effects of impact, contact, or other forms of attack. It can absorb or redirect force, spread it across a wider area, or make an attacker’s contact less effective. In cyber security, the term is also used more broadly for safeguards that help protect systems, such as endpoint protections or hardened infrastructure.
In real attacks and defenses, armor is only useful if it holds up under the conditions it is meant to face. Physical armor may be tested against repeated impacts; cyber defenses are evaluated against active attempts to find and exploit weaknesses. A barrier can also change how an attack interacts with a target rather than simply resist it. The key is to test protection against realistic threats instead of assuming that an unusual or sophisticated design works.