A more thorough explanation:

A standard is a model or criterion that is accepted as correct by custom, consent, or authority. It is used to measure acceptability, quality, or accuracy.

For example, in the ant-farm industry, there is a standard for how the ant farm should be designed and maintained. This standard is accepted by the industry as the correct way to care for ants.

In legal terms, there are two types of standards: objective and subjective. An objective standard is based on conduct and perceptions external to a particular person. For instance, in tort law, the reasonable-person standard is considered an objective standard because it does not require a determination of what the defendant was thinking. On the other hand, a subjective standard is peculiar to a particular person and based on the person's individual views and experiences. In criminal law, premeditation is determined by a subjective standard because it depends on the defendant's mental state.