This is one of the best project i have made. In this project i control the home lights by using GSM i.e. to send commands to the GSM module (SIM900) using text message to control the lights from anywhere in the world. The Sim900 Module received text messages from the user and sends commands to the Microcontroller the microcontroller identify the received command and then performs the specified condition. I used relays to drive the output load which were control by the Microcontroller. If certain appliance is on the SIM900 also sends text message to the user for making sure that your device is on. The whole project coding is done in C language by using Arduino compiler