This little sensor contains temperature, humidity, barometric pressure, and VOC gas sensing capabilities. All over SPI or I2C at a great price!
Like the BME280 & BMP280, this precision sensor from Bosch can measure humidity with ±3% accuracy, barometric pressure with ±1 hPa absolute accuracy, and temperature with ±1.0°C accuracy. Because pressure changes with altitude and the pressure measurements are so good, you can also use it as an altimeter with ±1 meter or better accuracy!
The BME680 takes those sensors to the next step in that it contains a small MOX sensor. The heated metal oxide changes resistance based on the volatile organic compounds (VOC) in the air, so it can be used to detect gasses & alcohols such as Ethanol, Alcohol, and Carbon Monoxide, and perform air quality measurements. Note it will give you one resistance value, with overall VOC content, but it cannot differentiate gasses or alcohols.