Any matter of fact that a party to a claim or action offers to provide to prove or disprove an issue in the case. The strongest type of evidence is that which provides direct proof of the truth of an assertion. At the other extreme is evidence that is merely consistent with an assertion but does not rule out other, contradictory assertions, and may be viewed as circumstantial evidence.

Also known as the external element or the objective element of a crime. It is the Latin term for a guilty act which, when proved beyond a reasonable doubt in combination with the mens rea, produces criminal liability.