system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How do companies get gases like oxygen and helium into canisters?
gpt
There are two ways to put gasses like He and O into bottles. Firstly, you can liquify them by cooling them under high pressure. Then you can put the liquid into the high pressure bottles, seal them, and allow them to warm up. The contents will then enter a state called 'super-critical', where they are neither liquid nor gas.

Secondly, you can take the gas and simply compress it, It will get hot as you do this, and you have to get rid of that heat. If the pressure is high enough, it will again become a super-critical fluid.

Lastly, there is another way to store and transport oxygen or helium. You can liquify it, and place it in a *dewar flask*, which is a container that is insulted by a vacuum. (A Thermos flask is a domestic dewar flask, and, indeed, they are often used to hold small amounts of liquefied gasses). The insulation is good enough to slow the boiling of the liquefied gas so that you can transport them long distances without losing too much of it.