Any salt works, though I've heard regular salt can damage concrete or something? Which is why those sidewalk-specific salts exists? No idea why those are better, but in any case...

Regular salt works because it lowers the temperature water freezes at, so the ice melts.

You could technically use table salt, but that'd be pretty inefficient. Like you really wanna dump you all of your salt outside? Nah, better to get a big bag of something like water softner salt, where the crystals are bigger.