An ideal gas is a gas consisting of particles that do not interact with eachother (particles can interact with elastic or point-like collisions while still following the ideal gas model.)1 The model is purely theoretical, but a useful approximation in many cases. All ideal gases follow the ideal gas law.
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Ideal gas. (2021). In Wikipedia. https://en.wikipedia.org/w/index.php?title=Ideal_gas&oldid=1005395290