Natural gas is a colorless, odorless, non-toxic, and non corrosive combustible gas, mainly composed of methane (CH4).

It has some alternative names in different contexts, mainly including the following:

1. "Gas": In daily life, people use "gas" to refer to natural gas, such as "running out of gas at home", "cooking with gas on", etc. Here, "gas" usually refers to natural gas.

2. "Gas": In some regions, natural gas is also called "gas", such as "gas pipelines" and "gas stoves". Here, "gas" mainly refers to natural gas, but sometimes it may also include other combustible gases such as liquefied petroleum gas.

3. "Methane gas": Because the main component of natural gas is methane, it is sometimes referred to as "methane gas", but this term is relatively rare and is mostly used in some professional situations.

4. "Pipeline gas": In urban gas supply, natural gas is transported to thousands of households through pipelines, so it is also called "pipeline gas" to distinguish it from bottled liquefied petroleum gas.

5. "Compressed natural gas" (CNG): When natural gas is compressed to a certain pressure and used for automotive fuel or other purposes, it is called "compressed natural gas".

 This form of natural gas is convenient for storage and transportation, and is often used in natural gas vehicles and other applications.

6. "Liquefied Natural Gas" (LNG): After natural gas is liquefied at low temperatures, its volume is greatly reduced, making it easier to transport and store. This liquid natural gas is called "liquefied natural gas".

 LNG is widely used in international trade and long-distance transportation.

These different names are named based on the composition, state, purpose, or mode of transportation of natural gas.