Natural gas is a nonrenewable fossil fuel resource because it cannot be replenished in a human time frame. Natural gas is a hydrocarbon mixture consisting primarily of methane and other alkanes.
It is an energy source often used for heating, cooking, and generating electricity. Before natural gas can be used as a fuel, it must be processed to remove impurities such as water so that it can meet the specifications of marketable natural gas.
Natural gas is often referred to simply as "gas", especially when compared to other energy sources such as oil or coal. However, it should not to be confused with gasoline, which is a different type of fuel. In North America, the term gasoline is often shortened in everyday speech to the term "gas" also.
As of 2009, there was an estimated total of 850 trillion cubic meters of remaining recoverable reserves of natural gas, whereas approximately 66 trillion cubic meters (or 8%) was already used by that time.
It is estimated that the world consumption rate is approximately 3.4 trillion cubic meters per year, according to 2015 sources, which means there is roughly 250 years of remaining economically-recoverable reserves in the world, if usage remains constant. However, an annual increase in usage of 2–3% could result in currently recoverable reserves lasting from 80 to 100 years.
So you don't have to worry about sources depleting any time soon.