Gods are a race of powerful beings who ruled over humanity. They reside in the Gods' Domain, a far place away from the Central Plain, and they were ruled by Tian before Shen Yen took control after Tian's fall.
Gods are able to overpower and rule humans due to their Divine Powers. Many of the Great Gods residing in the Gods' Domain look down on humans, calling them monkeys at best or creatures barely worthy of attention. Human lives are of little importance to them, and they believe that the humans' absolute supplication to them is the natural order.
There are some who disagree, though: the Fallen Ones, who rebelled against Tian and this viewpoint, retreating to the Central Plain to hide from Tian's wrath and live equally with the humans. While they believe that Gods and Humans are on equal footing, they nonetheless tend to remain separated from Humans due to the fact that they are being hunted down for their beliefs.
Physically, Gods look very much like humans; some will have extraordinary features like body markings or extra eyes, such as Shen Yen and Tian Kui, but for the most part, they are nigh-indistinguishable from humans by appearance alone. The most sure way to distinguish Gods by their physical appearance is with their blue eyes.