A Seeed Studio Temperature & Humidity Sensor is a digital environmental sensor capable of measuring temperature, humidity and other environmental factors. It can be used to detect changes in climate and atmosphere. The sensor has a wide range of applications, such as controlling fan speeds or other environmental systems, indoor temperature/humidity monitoring, or as part of an alarm system. The sensor's design also makes it perfect for low-cost Arduino projects. It uses a digital interface and can output real-time data via I2C communication protocol. It also has a wide range of operating temperatures (-40°C~85°C) and humidity ranges (0~100%). It also has high accuracy (± 0.3°C for temperature and ± 2% for humidity). It is powered by a single-cell lithium battery, and comes with a 5V power supply. The size of the sensor is 30x30x20mm.