Surveillance investigation is a critical method used by law enforcement, private investigators, and intelligence agencies to monitor individuals or groups discreetly. It involves tracking movements, recording activities, and gathering evidence for legal or security purposes. Techniques include physical observation, electronic monitoring, and GPS tracking. Surveillance is commonly used in criminal investigations, corporate espionage cases, and fraud detection. Investigators must operate covertly to avoid detection while ensuring accurate documentation of findings. Successful surveillance requires patience, attention to detail, and the ability to adapt to changing situations. This method plays a key role in uncovering hidden truths and ensuring justice.