In the novels of the apocalypse, there were usually levels to differentiate people or creatures with different abilities, strength, equipment, and power. These levels are usually divided according to the following criteria: [1. Strength level: Usually, it is divided according to a person's attack, defense, resistance, and other indicators.] The higher the attack, the higher the defense, the stronger the resistance, and the higher the level of strength. 2. Equipment Level: It is usually divided according to a person's equipment, including weapons, defensive equipment, medicine, etc. The better the equipment, the higher the level of strength. 3. Level system: Some novels will set a level system such as age, combat experience, mission completion, etc. Each level has a specific mission and benefits. 4. Organization Level: Some novels would use the organization level to differentiate between different forces or teams. The level of an organization was usually divided according to the size, strength, influence, and other indicators. In the novels of the apocalypse, the concept of hierarchy was very important. It could be used to differentiate between different strengths and forces. It was also one of the common plots in many novels.