Global warming is an increase in the average temperature of the Earth's surface. It takes place as a result of an increased concentration of greenhouse gases in the atmosphere.
The greenhouse gases include carbon dioxide, methane, nitrous oxide and ozone. These gases trap solar radiations or the heat released by the Earth. Sometimes this helps in keeping our planet warm and helps in human survival.
However, an increase in the amount of greenhouse gases can lead to an increase in the Earth's temperature, thus leading to global warming.