Items are objects you can obtain in-game. They have a wide variety of uses, properties and functions. Some such as weapons, auras and armour can be worn. Other items are transformed by using skills. Many can be harvested from the resources in the game. Lots of items are used or provided by quests. Many items have requirements which must be obtained in order to use them. This can include a Quest requirement and/or one or more levels in certain skills (which must be matched or exceeded). Items which can be worn are known as Equipment - these often have statistics which benefit the player when they are equipped (worn).
There are currently about a total of 8,300 items in-game. Around 4600 of them are untradeable. There are 47 items who don't have a function and are useless.