There are 4 different Attributes that a person may choose from when creating his/her character. The choice directly effects what skills they learn and also what stats they SHOULD put their points into. These four attributes are Earth, Water, Fire, and Wind.
Earth has a higher defense power. Earth can defeat water but is weak against wind.
Earth attribute can also learn important support skills like Stone Wall(which negates physical attacks),Terrafication(Which seals for 4 rounds) and Many others.
Earth Attribute characters are either tanks or sealers in quest.
Water is great at assistance attacks. It can defeat fire but is weak against earth. Waters can learn very useful skills like Sleep(Aoe Stun) and Revival. Water Attribute characters are usually supporters or sealers, their general purpose is to seal and revive during quests.
The most secret hiddden skills.
Fire has a higher attacking power. It can defeat wind, but is weak against water. Fire element players are mostly attackers in the quest by having either high STR or high INT which makes them important when questing.
The only attribute without a secret hidden skill.
Wind has higher agility and speed. It can defeat earth but is weak against fire. They are also naturally the fastest element in WLO (subject to change based on other elemental's stats).