Hearsay evidence is a legal term that refers to an out-of-court statement or assertion made by someone other than the person testifying in court, which is offered as evidence to prove the truth of the matter asserted in the statement. In other words, it is a statement made by a person who is not testifying in the current legal proceeding but is being presented in court to prove that what was said in the statement is true.

Hearsay evidence is generally not admissible in court because it is considered less reliable than firsthand testimony. The rationale behind the hearsay rule is that when someone repeats what another person said, there is a greater likelihood of inaccuracies, misinterpretations, or dishonesty compared to when a witness testifies based on their own firsthand knowledge.

However, there are exceptions to the hearsay rule, and in certain circumstances, hearsay evidence may be admitted in court. These exceptions vary by jurisdiction but often include statements made by a party-opponent, statements made for medical diagnosis or treatment, statements made under oath in a prior proceeding, and statements made in the regular course of business records, among others.

It's important to note that the rules regarding hearsay evidence can be complex, and their application may depend on the specific legal jurisdiction and the circumstances of the case. Attorneys and judges are responsible for determining whether hearsay evidence should be admitted or excluded in a particular legal proceeding based on the applicable laws and rules of evidence.