Coolant can be pinkish or greenish, but most of the time you'll find the green variety. It has a sweet smell and is somewhat viscous.
Did you know that as coolant breaks down, it can begin to react with the metals inside your cooling system, eventually breaking it down and causing a major leak? A number of vehicles that used aluminum heater cores are very prone to this type of mess, which results sometimes in hot coolant being sprayed all over the driver's feet! It's a good idea to flush your radiator annually to avoid any chance of this.