Evidence consists of physical objects, testimony, or other things offered in court to prove or disprove the existence of a fact. There are several types of evidence that may be direct or circumstantial evidence, depending on how the evidence is used at trail. The presentation of evidence during trail is also governed by principles called rules of evidence. Please define the following rules of evidence: best-evidence rule, chain of custody, competency to testify, hearsay, relevancy, cumulative or unduly prejudicial evidence, privilege, and lay opinions.