Materia System Explained (Final Fantasy VII)

This guide will explain the Materia System of Squaresoft/Square-Enix's Final Fantasy VII. So, what is the Materia System? It is how your playable characters gain anything more than the five basic commands: Attack, Item, Limit, Defend, and Row. It also how they summon, cast magic, and add another way of effecting stats, among other things. This guide will not list all the materia in the game (though I plan on doing so in a different guide), but it will explain how it works.

Types of Materia
Magic
These materia are colored green and add the "Magic" command to the character's command list. They usually decrease physical stats and increase magic stats. Leveling up a Magic materia usually adds new spells to it.

Summon
These materia are colored red and add the "Summon" command to the character's command list. They usually decrease physical stats and increase magic stats. Leveling up a Summon materia increases how many times they may be summoned in a single battle.

Command
These materia are colored yellow and can add a variety of different commands to the character's command list. Sometimes, they can even modify or completely change an existing command! Command materia often slightly increase one particular stat. Leveling them up can alter or add commands to the materia.

Support
These materia are colored blue and work with other materia, never alone. This is always true...not a single Support materia will work by itself; they must be linked to other materia (which will be explained later). Usually, they do not affect character stats and work best with Magic and Summon materia (though a few work with Command materia). Leveling them up often increases how many time the Support materia's effect can be used in a single battle.

Independent
These materia are colored purple and are just the opposite of Support materia...they always work alone. No amount of linking other materia to them will change that. Independent materia increase or decrease various stats and/or create a special effect in or out of battle.

How the System Works
It's pretty basic. Your weapon and armor each have slots in them to hold materia (though a few have no slots at all). If you place a materia in those slots, the character gains the ability to use whatever that materia has to offer, and feels the positive and negative effects of the materia (i.e. stat changes). These abilities and effects go away once you remove the materia, and they are never permanently learned on that character (but are for that materia). When you select a materia, the box on the bottom left hand corner of the screen will have information about the materia. You'll see how much AP (Ability Points, which will be explained soon) it has gained, how much AP it needs to go up a level (measured by stars), the name of all the abilities it has to offer (lit up words are those that the character currently has), and how the materia affects the character's stats.
Finally, about AP...after every battle, you will see how much EXP (Experience Points), AP, and Gil you won for your victory. AP is just like EXP, only it goes to your materia. Once a materia has gained so much AP, it levels up. Weapons and armors can affect how much AP you get. When you select a weapon or armor, you will see "Growth" on the screen, and out beside it either "Normal", "Double", "Triple", or "None". "Normal" means your materia gains the amount of AP it says you did after battle. "Double" means your materia gains that much AP times two. "Triple" means your materia gains the amount of AP it says you did times three. "None" means your materia gains no AP. These increases and decreases only apply to the materia in that particular weapon or armor.

Equipping Materia
First, go to the Equip menu from the main menu. Notice all the empty black holes (or dots, your pick) under the names of your weapon and armor? Those are called materia slots and, obviously, they hold your to-be-used materia. You can either just equip materia here or form combos.
Press confirm over your selected slot, pick your materia, and it will be placed there. If another materia already occupies that slot, the two will be exchanged.

Combos
To form combos, you need either a pair of slots that are linked (linked slots look like this: O=O) or an Independent materia with a special effect. In the case of linked slots, any two materia can go in those slots, but a Support materia must be one of them for a combo effect. The other slot must be filled with either a Magic, Summon, or Command materia. Please note that a Command-Support materia combo is very rare, as most of them won't work, but there are a few.
The most common materia combo are the [Magic materia]=All combo. "All" is a Support materia that makes the linked spell affect all enemies or allies. It works wonders with a Restore materia. However, "All" is horrible with Summon materia, as most already hit all enemies to begin with. A common (but late-game) Summon-Support combo is the Phoenix=Final Attack combo. "Final Attack" works when the character it is on is KO'd...once this occurs, they automatically use the linked materia. "Phoenix", when summoned, revives all allies and deals Fire damage to all enemies. Linked with "Final Attack", it will almost assuredly keep your characters alive and weaken your foes.
What about Command materia? There are a few Support materia that go with them, name "Counter". This support materia, when linked to a Command materia, will make the character who equipped it strike back with that command when attacked. So, if "Counter" is linked to the "Mime" Command materia, the character will retaliate (not always, no counter is ever 100% in occurrence) by mimicking the last action his/her ally did. Commands that modify or change an already existing command will not work here (this includes Mug).
Lastly, Independent materia can make for interesting combos. The most popular one is perhaps the most simple: the "Mega All" Independent materia gives "All" to all of that character's commands. So, if the character has for his materia "Fire", "Restore", "Barrier", and "Mega All", then not only will the character's Fire, Curative, and Barrier spells affect all enemies or allies, but so will his/her attack command! And all without a single linked slot.

Elemental and Added Effect Materia
These are among the most interesting and useful combinations. I will not list them here, however, as I already have an Elemental Guide on this site and will work on making an Added Effect Guide, if I think it is needed (or if I need to kill time).

What Won't Work
These combos listed below will not work. Ever. They have been tried many times in many different ways.

Knights of Round=Quadra Magic
Too powerful. "Knights of Round" can already hit thirteen separate times in one summoning; why would anyone need to summon all thirteen knights four times in a row for the cost of one summoning? Let's leave a bit of challenge. Using the "HP=MP" Independent materia will not make it work either.

Double Cut, Mega All
Contradictory. Both 2X-Cut and 4X-Cut replace the Attack command, and "Mega All" changes Attack to Slash-All. So, the game goes with "Mega All". However, if you're using the "Slash-All" Command materia and "Double Cut", whichever of those two is lower and more to the right on your materia slots is the one you use. "Mega All", however, always overrides them.

There you have it. I will add more as I see fit.
Thanks to Squaresoft (now Square-Enix) for making this great RPG.

~NovaYou know the drill. All comments and suggestions welcome.
Materia: condensed Mako energy than grants the user the wisdom of the Ancients. Useful stuff, and a great time killer. Broken as all hell, though.