Machine monitoring refers to any method of connecting machine data streams to the internet in order to provide real-time production monitoring and sophisticated production data analytics. The most common type of machine monitoring system is the industrial sensor, which collects data from sensors on machinery or other physical processes and sends it to a server for analysis. Industrial sensors can be divided into three main categories: analog inputs, digital inputs, and hybrid inputs. Analog inputs convert continuous variable signals into discrete pulses that can be read by computers. Examples include temperature sensors, flow sensors, and pressure sensors. Digital inputs use transistors to measure electrical resistance or optical signals to detect the presence of particles or fibers. They provide greater accuracy than their analog counterparts but cannot directly measure temperatures or pressures. Hybrid inputs combine both analog and digital technology to provide improved performance over either type of input device alone. For example, they may use infrared thermometers with air quality monitors to give an overall picture of equipment health. Sensor networks consist of multiple sensors that collect data about the same subject but are located at different locations. These individual pieces of information are combined to create a complete picture of what is happening within the monitored area. Sensor networks are used in a variety of applications including environmental monitoring, military surveillance, healthcare facilities, and building automation systems.