Hall effect sensors are devices that detect the presence and strength of a magnetic field. They operate based on the Hall effect, which occurs when a current-carrying conductor is placed in a magnetic field, causing a voltage to develop across the conductor. This voltage can be measured and used to determine the magnetic field's characteristics. These sensors are commonly used in various applications, such as in automotive systems for detecting the position of rotating shafts or in smartphones for detecting the opening and closing of covers. Their compact size and reliability make them ideal for many electronic devices and systems.