A signal jammer is a device that disrupts communication signals by emitting radio frequency signals that interfere with the normal operation of electronic devices. These jammers can block various types of signals, including those used by mobile phones, Wi-Fi networks, and GPS systems. They are often used in situations where communication needs to be restricted, such as in certain military operations or secure facilities. The use of signal jammers is illegal in many countries, including the United States, due to their potential to disrupt emergency communications and public safety. While they can be effective in preventing unauthorized communication, their deployment raises ethical and legal concerns regarding privacy and the right to communicate freely.