I hope reading it will help people with grasping the concepts of threshold, attack, release etc.
It looks like a helpful starting point, but it's technically incorrect in the way it describes attack and release.
In most cases attack and release simply control how fast gain is changed. They are only indirectly related to threshold crossings. Once the signal rises above the threshold the gain calculator uses the ratio and knee settings to produce a target gain value, the attack and release settings control how fast the target gain value changes and that value is sent on to the gain controller (see
Rane Note 155). They affect the sound any time the gain calculator's target gain value changes, regardless of threshold crossings.
You can demonstrate this easily with an amplitude modulated signal and a compressor with a
threshold below the quietest part of the signal so there are no threshold crossings, like this:
Uncompressed:
Compressed: