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.

The responsibility of a person to pay a debt or other financial obligation. If an individual signs a promissory note, that individual usually has full personal liability for the debt. An exception is the unusual situation of a non-recourse individual loan, in which the lender agrees to look only to the collateral for recovery in the event of default.

The causal relationship between conduct and result, especially when proving legal responsibility. This is a key component in establishing liability in both criminal and civil law.