Gray hat SEO techniques combine white hat and black hat SEO techniques, using white hat techniques that are just within the limits of becoming black hat. It is important for SEO professionals to understand gray hat techniques because they can improve rankings without penalties, but risk lost traffic if they violate Google's guidelines. While gray hat strategies may change over time, it is generally safest for businesses to strictly follow white hat SEO and avoid any tactics of uncertain status due to the risk of Google penalties.