Sensors are devices that detect events and read changes in its environment, be it rotation and vibrations from machines, motion detection or temperature readings. Sensors play a very prominent role in the making of IoT as it can be programmed to sense the required environmental parameters that need to be monitored and convert them into meaningful data. Sensors by itself do not have input and output control or functions. The sensed information can be viewed in a console connected to another device like desktop or mobile. Sensors come in connected form and a single form. Connected sensors are a network of sensor nodes that capture information from the physical object or resource within a particular area and send the information over the network. For example, a collection of smart water sensors that measure the quality of water and indicate pollution levels by sensing different polluting ingredients in the water. A single sensor is a standalone device that emits signals based on the target object’s movement. It could also be as simple as making an alert beep at regular intervals. For example, a medicine bottle may have a sensor that alerts with a beep to indicate the patient that it is now the time to take the medicine. Sensors may or may not be instructed. For instance, some sensors may be instructed to control its behavior through low-level programming API and information from the sensor is transmitted via a device gateway. Some sensors may have the capability to directly transmit the information to the internet. Sensors are low powered device and often equipped with a small longer life battery that runs for months or even years. Some sensors are even powered using solar energy.