The New York City Police Department (NYPD) actively monitors public activity in New York City, New York, United States. Historically, surveillance has been used by the NYPD for a range of purposes, including against crime, counter-terrorism, and also for nefarious or controversial subjects such as monitoring political demonstrations, activities, and protests, and even entire ethnic and religious groups. The NYPD has credited surveillance systems as preventing numerous terrorist attacks on the city and helping to provide evidence for hundreds of criminal cases.