Combat Levels
First you need to know what a combat level is and what you can do with it.
The combat level contributes to the combat skills of a player or NPC. Generally, the higher the combat level, the more skilled the player or NPC is in combat. Higher your level is, more easily you will get the RuneScape Money.
We should note an important that combat level is based upon the armour and weapons that an NPC has, natural or equipped. For example, a black dragon has a higher combat level not only due to its natural Strength, but also because of its natural armour (dragonhide) and weapons (claws and fire breath).
Person’s (or NPC's) combat level will be displayed when you hover your mouse cursor over an NPC or player.
Green Combat levels mean that you have a higher combat level. red Combat levels mean you have a lower combat level. If the colour is yellow, it means the player has a similar combat level to you, or the NPC is within your combat level range.