Question: What are stars made of ??

Ciarán O'Brien answered on 21 Nov 2014:

Mostly hydrogen gas, only heated up so much from the pressure of gravity that most of it’s gone beyond solid/liquid/gas and turned into plasma, the fourth state of matter.

Stars contain other elements too, in numbers that increase over its life. Stars burn by converting their hydrogen into helium. Some of the helium will fuse together too to make heavier elements, and those will combine to make some heavier elements, and so on. But these elements are in much smaller quantities because hydrogen is so plentiful and so easy to burn. Most of the heavier stuff forms when the star is running low on hydrogen and needs to burn other stuff to keep going.

Still, stars are so big that even small amounts of these heavier elements would add up to millions of tonnes.