As cetawin said, a sex link is a crossbreed whose sex can be determined at hatch due to a color difference so no waiting to find out the sex later. You know instantly. The most common one would be a RIR rooster over a Barred Rock hen, though there are others. A Delaware rooster over Barred Rock hen yields a sex linked chick, apparently. All males have a head spot and females will be solid colored. I have only one female from that cross, Raven here (named thus because she resembles one)
