Runes are small stones with special magical bonuses that can be inserted into socketed items in order to supply them with the rune's special magical bonuses that each rune has.
Extra Info
The Runes can also be used in order to create RuneWords
RuneWords are special socketed items with specific runes with the correct order inside a socketed item with the exactly number of sockets and with the correct item type as each RuneWord Formula requires.
When you make a RuneWord using a specific Formula the RuneWord that you will have after that will not only have the Formula's bonuses but also each rune's bonuses that's inserted into the socketed item.
Runes can also be used in order to :
Craft Items ,Repair Items ,Socket Items ,Upgrade Items and Cube Runes.
Note
The Runes can be divided into 3 major categories the Low Runes the Medium Runes and the High Runes.
Low Runes are called the runes from El to Amn .

Medium Runes are called the runes from Sol to Um.

High Runes are called the runes from Mal to Zod.

|