From vincent wong on hackster.io:
This is a simple project using a MQ4 gas sensor, together with Netduino 3 WiFi. The LED light will turn on if the gas sensor’s value is above certain threshold. To ease my testing, I add a light sensor so that I can turn on and off the LED by changing the resistance.
Read more and see more on YouTube
Here at Adafruit, we sell all of these amazing components, but we couldn’t find a good way to interact with them over the internet. There are certainly a lot of great services out there for datalogging, or communicating with your microcontroller over the web, but these services are either too complicated to get started, or they aren’t particularly fun to use. So, we decided to experiment with our own system, and that is how Adafruit IO got started.
To start, please visit https://io.adafruit.com, and take a look around.
Want to get started quickly? Get up and running with the Welcome to Adafruit IO Guide on the Adafruit Learning System.
Experiencing issues or problems? Join us in the forum or on Discord in the adafruit-io channel with questions, comments, or suggestions.
We also have a blog/changelog specifically for Adafruit IO to keep you updated with the latest changes to Adafruit IO.
To make it easy for people to get started using Arduino or ESP8266 we have a starter pack with just about everything you may want to connect to the internet, with known-working WiFi modules!
ESP8266 Huzzah Kit