Zero Day

What Does Zero Day Mean?

Zero day, in IT, refers to the first day that something is known or anticipated. This term is applied in various ways: for example, the first day that a team of security workers or other party discovers a virus, it is called a "zero day" virus. In other words, zero day is that first day that someone identifies a problem and tries to address a security threat or other IT issue.


Techopedia Explains Zero Day

In addition to a "zero day virus," IT professionals may talk about a "zero day attack" or a "zero day threat." Zero day is used as a benchmark: often, security teams continue to keep careful track of the number of days that a security issue has been addressed. This is usually done in order to track progress, until a security issue or other IT issue is resolved or closed.

Another role of the term "zero day" is to describe the processes that security workers encounter. Someone might talk about how many "zero day" attacks or threats they found on a given day. Another example is of specific "zero day" vulnerabilities found in the workings of an operating system. As a core software resource, the operating system has a lot of context, and that means that zero day issues carry a lot of this context also. The kinds of new security problems that pros find can be politicized, and affect an OS brand while generating the same kinds of controversy and collaborative fixes that other zero day finds typically involve.


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Margaret Rouse

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.