Compressing a gas in this manner leads to an increase in the pressure on the gas. We discussed earlier that we can convert a gas to a liquid by cooling the gas. As this animation shows, we can also increase the pressure on it. The high pressure makes the molecules get closer and turn into a liquid.

In fact, the LPG in LPG cylinders stands for Liquified Petroleum Gas. Though LPG is a gas when it reaches the stove, when it is inside the cylinder, it is a liquid. The reason it is a liquid is because the cylinder has a very high pressure inside.