"Self-incrimination" refers to any statements, testimony, or information that exposes the speaker, or leads to other information that may expose the speaker to the possibility of criminal prosecution.
Under the Fifth Amendment to the United States Constitution, the government may not require people to make self-incriminating statements that might be used against them in a criminal proceeding. When an individual "Takes the Fifth" during questioning by law enforcement, he or she is invoking the Constitutional right against self incrimination and asserting his or her right to remain silent. This Constitutional protection applies only to statements or testimony, not to physical evidence such as fingerprints, DNA, hair, blood or urine samples.
If you or someone you know is being criminally investigated, consult with an experienced criminal defense attorney before speaking to law enforcement. Any self-incriminating statements provided to law enforcement can be used as evidence during the trial, or other criminal proceedings.