In criminology, evidence refers to any physical or verbal information that can be presented in court to prove that a crime was committed. Evidence can come from various sources, such as genetic material, trace chemicals, dental history, fingerprints, and eyewitness accounts. Evidence can be classified as direct or circumstantial. Direct evidence provides information that is considered to be true beyond a reasonable doubt, such as a videotape that shows the defendant committing the crime. Circumstantial evidence, on the other hand, requires the judge to make inferences or assumptions to reach a conclusion, such as a fingerprint found in a location connecting the accused to the victim or the crime scene.

Physical evidence is any tangible evidence that can be presented as an exhibit, such as weapons or other instruments used to commit the crime, illegal contraband, DNA, blood, photographic or video footage, footprints, and scientific and forensic evidence. Demonstrative evidence, such as photographs of the crime scene, is not real evidence but only illustrates the point.

The outcome of a case relies on the strength of the evidence presented, and the evidentiary rules are strict in terms of the responsibilities of both parties to preserve evidence. Any intentional, reckless, and/or negligent hiding of evidence by either party to the proceeding is considered illegal. Evidence forms the building blocks of the investigative process, and for the final product to be built properly, evidence must be recognized, collected, documented, protected, validated, analyzed, disclosed, and presented in a manner that will be acceptable to the court.

Different types of evidence include:

• Testimony
• Documents
• Photographs
• Videos
• Voice recordings
• DNA testing
• Tangible objects

In the US, federal courts follow the Federal Rules of Evidence, while state courts generally follow their own rules. Rules of evidence concentrate first on the relevancy of the offered evidence, and the admissibility of hearsay and oral testimony are addressed under Article VIII of the Federal Rules of Evidence. Rules of evidence also allocate among the parties the burden of producing evidence and the burden of persuading the court.