Item

An Item is an artifact/object carried by champions to enhance their performance on the Fields of Justice. Items are only obtainable through the Item Shop located at the resurrection platform, where they are displayed in five main categories (by their effect). They can also be divided by their Tier: basic, advanced and legendary. A champion can only carry 6 items at a time, making the selection of items an important part of achieving victory.

Item Store
The item store is next to the champion's summoner platform on any map. Also you are able to buy from the enemy shop if you are close enough to it. It is accessible by left-clicking the shopkeeper or by pressing the "P" key. Items are only purchasable when nearby the shop, but can be viewed from anywhere.

The item store menu is structured as follows:
 * Defense
 * 1) * Health
 * 2) * Magic Resist
 * 3) * Health Regen
 * 4) * Armor
 * Attack
 * 1) * Damage
 * 2) * Critical Strike
 * 3) * Attack Speed
 * 4) * Life Steal
 * Magic
 * 1) * Ability Power
 * 2) * Cooldown Reduction
 * 3) * Mana
 * 4) * Mana Regen
 * Movement
 * Consumables

On the top right side of the shop window, there is a champion-specific interface with six recommended items selected by the Riot Games staff. These recommended items are useful options when you do not know what to purchase.

Effects
Every item in the game grants one or more primary statistics to a champion. More expensive items may also grant one or two secondary effects. Sometimes an effect is listed as UNIQUE, which means that if two identical items are bought, the unique effect will apply only once, (also referred to as a non-stackable effect). However some Unique Passives from different items do not stack like Archangel's Staff, Manamune and Tear of the Goddess

Primary effects
Primary effects affect the champions themselves, and can increase the following statistics:
 * Ability Power
 * Armor
 * Armor Penetration
 * Attack Damage
 * Attack Speed
 * Cooldown Reduction
 * Critical Strike
 * Dodge
 * Health
 * Health Regeneration
 * Life Steal
 * Magic Penetration
 * Magic Resistance
 * Mana
 * Mana Regeneration
 * Movement Speed
 * On-Hit Effects
 * Spell Vamp
 * Tenacity

Secondary effects
Secondary effects are divided into three categories:
 * 1) Active: An item that has an ability which can be activated by clicking on the item icon in the inventory or using the number pad keys 1-6 by default.
 * 2) Aura: It can be an area of effect buff that affects you and your allies and/or minions, or a debuff that affects your enemies and/or their minions.
 * 3) Passive: An item that has an ability that works automatically, like a passive ability.