Miranda v. Arizona, 384 U.S. 436 (1966), was a landmark decision of the United States Supreme Court. The Court ruled that a suspect in police custody must be informed of the right to consult with an attorney before and during questioning. They must be informed of the right against self-incrimination. They must also make certain the suspect understands these rights.
The Miranda warning (often abbreviated to "Miranda," or "Mirandizing" a suspect) is the name of the formal warning that is required to be given by police in the United States to criminal suspects. It must be given before they are interrogated, in accordance with the Miranda ruling. Its purpose is to ensure the accused are aware of these rights under the U.S. Constitution. Also so they know they know they can invoke them at any time during the interview.