A warrant is a legal document issued by a judge or magistrate that authorizes law enforcement to take a specific action, such as searching a property or making an arrest. It is based on probable cause, meaning there is reasonable belief that a crime has been committed or that evidence of a crime can be found in a particular location. Warrants are essential for protecting individual rights under the law, as they require law enforcement to provide justification for their actions. This process helps ensure that searches and arrests are conducted fairly and legally, maintaining the balance between public safety and personal privacy.