A jammer or blocker is a device designed to disrupt or interfere with communication signals. These devices can block various types of signals, including those used for mobile phones, GPS, and Wi-Fi. Jammers work by emitting signals on the same frequency as the targeted communication, effectively preventing devices from receiving or transmitting information. Jammers are often used in specific situations, such as in military operations or secure facilities, to maintain privacy and security. However, their use is heavily regulated in many countries due to potential misuse and the impact on emergency communications. Unauthorized use of jammers can lead to legal consequences.