I am studying electromagnetism and have encountered the Heaviside-Lorentz unit and Gaussian unit. In these unit systems, the constant $c$ keeps occurring. For example, the Maxwell equations are of this form.
So, I think in these unit systems, $c$ is some nontrivial constant other than $1$. However upon reading the Wikipedia about natural units, it states that the Heaviside-Lorentz unit and the Gaussian unit are natural units and $c=1$. So I am confused. Why does $c$ keep occuring in the two units if $c$ is jus equal to $1$? Could anyone please explain?
https://en.wikipedia.org/wiki/Natural_units#Electromagnetism_units : This is the link to the Wikipedia about natural units that I read.