Ares or any other P2P programs

Are these legal to download from ? I heard you are able to download anything but you can’t sell it to others. I am just wondering if this is true or not. I do not want to cause any trouble for myself if it is illegal.

Many countries downloading copyrighted content is illegal, most countries sharing copyrighted content is illegal.
P2P downloads & uploads simulataneously, so it’s get you in both cases.

Of course, there is nothing illegal with the actual P2P programs, if you just download copyright-free content, aka public domain content.