The privilege against self incrimination refers to declining to make statements or produce evidence which tends to prove that one is guilty of a crime. The 5th Amendment to the U.S. Constitution, which is applied to state cases under the 14th Amendment, guarantees that one cannot "be compelled in any criminal case to be a witness against himself…" Therefore, when a person "takes the Fifth", they are refusing to testify in court on the basis that the testimony may be self-incriminating.
A person may choose, with certain restrictions, to “take the Fifth,” refusing to testify in court or before a legislative or executive committee. Prohibiting self-incrimination not only helps guarantee due process of law, but also maintains one of the basic principles of American law by putting the burden of proof on the prosecution. The privilege against self-incrimination is a personal one. It applies to individual persons only. A corporation cannot "plead the Fifth" in order to keep quiet. Also, it only applies in criminal cases. A witness cannot keep silent or withhold information in civil proceedings.