I heard people say road cycling or cycling in general is 'low impact' in regards to your body, what is meant by this?

Does this mean it won't damage your body as much as say running, or it won't work your body out as much as a work out... or both?

What is meant by Low impact?

It's just I read some where that cycling was classed as 'no-impact'... So where is the line drawn or is it like everything else in this internet age factual information is all subjective as everyone seems to be a 'pro' at giving advice.