Ethene is the member of the alkenes which contains two Carbon atoms, giving it the formula C2H4
Ethene is a colourless gas at room temperature; it is flammable and has a slightly sweet, fruity smell.
Ethene is produced industrially - in order to form the basis of many of the polymer plastics we use every day - by fractional distillation from either natural gas or petroleum, to form alkanes, which are then heated at very high temperatures in steam, producing ethene and Hydrogen, in a process called steam cracking.
Ethene is an important hormone in plants, promoting fruit ripening and shoot growth, among other processes.
Banana-ripening warehouses treat green bananas with ethene to get them ready for the supermarket shelves!