Replacing the use of books to upgrade spell levels is the new feature known as Skill Trees.
Each character class has a unique set of 30 spells, 10 for each tree, making 3 trees for each class.
It is recommended by the Blizzard Diablo II Developers that a player specialize in one of the trees and not try to be a jack of all trades.
Spell Tomes are able to be found which are used to store up to 20 scrolls in.
This way you can carry 20 scrolls of town portal or identify and only take up 2 spaces, while in Diablo that would be impossible.
Each Class has skills set to match and help that particular class. The Amazon, for example, has skills in bows/crossbows, javelins/spears, passive/magic.
Theoretically, an amazon could add a point to each skill in each tree and then begin to specialize in one, remembering though that defensive play in diablo was not always the best, neither was only attacking...

- Jab »
- Impale »
- Fend
- Power Strike »
- Charged Strike »
- Lightning Strike
- Poison Javelin »
- Lightning Bolt »
- Plague Javelin »
- Lightning Fury

- Inner Sight »
- Slow Missiles »
- Decoy »
- Valkrie
- Dodge »
- Avoid »
- Evade
- Critical Strike »
- Penetrate »
- Pierce

- Cold Arrow »
- Ice Arrow »
- Freezing Arrow
- Magic Arrow »
- Multiple Shot »
- Guided Arrow »
- Strafe
- Fire Arrow »
- Exploding Arrow »
- Immolation Arrow

- Howl »
- Taunt »
- Battle Cry »
- War Cry
- Shout »
- Battle Orders »
- Battle Command
- Find Potion »
- Find Item »
- Grim Ward

- Sword Mastery
- Axe Mastery
- Mace Mastery
- Pole Arm Mastery
- Throwing Mastery
- Spear Mastery
- Increased Stamina »
- Increased Speed
- Iron Skin »
- Natural Resistance

- Leap »
- Leap Attack »
- Whirlwind
- Bash »
- Stun »
- Concentrate »
- Berserk
- Double Swing »
- Double Throw »
- Frenzy

- Prayer »
- Vigor »
- Meditation
- Defiance »
- Cleansing »
- Redemption
- Resist Fire »
- Resist Cold »
- Resist Lightning »
- Salvation

- Might »
- Blessed Aim »
- Concentration »
- Fanaticism
- Holy Fire »
- Holy Freeze »
- Holy Shock
- Thorns »
- Sanctuary »
- Conviction

- Sacrifice »
- Zeal »
- Vengeance »
- Conversion
- Holy Bolt »
- Blessed Hammer »
- Fist of Heavens
- Smite »
- Charge »
- Holy Shield

- Dim Vision »
- Confuse »
- Attract
- Amplify Damage »
- Iron Maiden »
- Life Tap »
- Lower Resist
- Weaken »
- Terror »
- Decrepify

- Poison Dagger »
- Poison Explosion »
- Poison Nova
- Teeth »
- Corpse Explosion »
- Bone Spear »
- Bone Spirit
- Bone Armor »
- Bone Wall »
- Bone Prison

- Skeleton Mastery »
- Golem Mastery »
- Summon Resist
- Clay Golem »
- Blood Golem »
- Iron Golem »
- Fire Golem
- Raise Skeleton »
- Raise Skeletal Mage »
- Revive

- Cold Mastery
- Frost Nova »
- Blizzard »
- Frozen Orb
- Ice Bolt »
- Ice Blast »
- Glacial Spike
- Frozen Armor »
- Shiver Armor »
- Chilling Armor

- Lightning Mastery
- Static Field »
- Nova »
- Thunder Storm
- Charged Bolt »
- Lightning »
- Chain Lightning
- Telekinesis »
- Teleport »
- Energy Shield

- Fire Mastery
- Inferno »
- Blaze »
- Fire Wall
- Fire Bolt »
- Fire Ball »
- Meteor
- Warmth »
- Enchant »
- Hydra
