Ice melt (a.k.a "De-icers) are products that lower the freezing point of water. So instead of forming ice, it remains liquid slush. Some different kinds of ice melts are sodium chloride (Rock Salt), calcium chloride pellets, and magnesium chloride pellets.
Ice melt should be applied before snow and ice is expected, or as soon as it arrives. You should also use ice melts after snow is cleared away.
Some ice melts are bad for concrete, especially if the concrete is cracked or was recently laid. However, ice melts like magnesium chloride and calcium chloride can be safe for concrete.
To clear an icy driveway quickly, first shovel any snow that's covering the ice. Then cover the driveway with rock salt, or magnesium chloride pellets, or calcium chloride pellets. Once the ice melts, shovel it away. If you're using rock salt, you can spray warm water to help the ice melt quicker.