What does the term 'Actus Reus' refer to in criminal law?

In criminal law, 'Actus Reus' specifically refers to the actual criminal act that is committed. This encompasses any physical action or conduct that constitutes a violation of the law. For a crime to occur, there must be an act that is explicitly forbidden by law, which distinguishes it from abstract criminal intentions or thoughts.

The concept is fundamental because it highlights that mere thoughts or intentions (which pertain to the mental state or mens rea) do not constitute a crime by themselves; there must be an observable action. This is necessary to establish the fact that a crime has been committed and aids in determining liability in legal proceedings. The definition and understanding of 'Actus Reus' are vital for establishing elements of various offenses within the scope of criminal justice.