Active skills require the L2 Adena player to manually select.
Learning the weapons and armor that best fit your character can mean the difference between winning and losing. Each of the character classes has armor and weapons that suit them better than anyone else, and some weapons are best used on specific enemies. Learning what weapons and armor are appropriate for the battle you are in is a big part of Lineage 2. You won't come out victorious unless you know what weapons and armor are appropriate for the current situation. There are over 1300 active and passive skills that you can apply to your character. That's an incredible amount of skill discovery and adds a lot to the games overall fun factor. Passive skills are active all the time and do not need to be manually triggered in order to be used. Active skills require the L2 Adena player to manually select and activate them in order to be used.