bug fix

In engineering, a bug is a design defect in an engineered system—such as software, computer hardware, electronics, circuitry, genome, or machinery—that causes an undesired result. Defects outside the scope of design, such as a server crash due to a natural disaster, are not bugs, nor do bugs occur in natural systems such as the weather.
Bug is a non-technical term; more formal terms, besides defect, are error, flaw, and fault. Bugs may be persistent, sporadic, intermittent, or transient; in computing, crashes, freezes, and glitches are types of bugs.
Since desirability is subjective, what is undesirable to one may be desirable to another, hence the often comical rejoinder occasionally offered to the report of a bug, "It's not a bug, it's a feature."

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