The Items

Here is a nice handy reference sheet that contains some information about all the items, weapons, and armor you can get in Zelda, whether it be through killing enemies or acquiring them. I'll write the more common name first, followed by the game's description of it in parentheses, where applicable. The list is organized alphabetically, except when there is a "pairing" of similar items (like the blue and red ring, etc).

Name of Item Picture Description Max Capacity How and Where do I get it? Extra Details
Single Rupy A Rupy is the money, moola, shinies in Zelda. You usually use it to buy stuff and information. 255 Defeating enemies, secret NPCs will give it to you, winning mini-games. Every arrow you shoot costs one rupy.
Five Rupies More rupies! This one is worth 5 of those orange ones. 255 Same as single rupies. The Ropes are good sources for Rupies.
Arrow Um, it's an arrow. You use it to shoot things from a distance. You carry as many arrows as you do rupies. You buy them from stores for 80 rupies. Every shot arrow costs one rupy.
Silver Arrows These are special arrows, you need them to defeat Ganon. You carry as many arrows as you do rupies. Found in the ninth dungeon. Same cost per shot as regular arrows.
Blue Candle It's a candle. You use it chiefly to light up darkened dungeon rooms. One candle, one use per screen. You buy it in stores for 60 rupies. Candles can also be used to damage some enemies and more importantly, can light bushes on fire, which can reveal secrets.
Red Candle It's an enhanced version of the Blue Candle. Same effects. One candle, can be used an infinite number of times per screen. Replaces the Blue Candle. Found in the seventh dungeon. I don't advise searching for secret burnable bushes until you get the Red Candle, with the Blue one it'll get very tedious.
Blue (Life) Potion Life giving potions. They refill all your life. One. Give the Letter to the old woman in one of the many caves where she doesn't say anything, and you can then buy them for 40 rupies. A blue potion can be used only once per purchase, but I recommend only buying the Red variety.
Red (2nd) Potion "Mega" Potion, it can be used twice instead of the Blue Potion's single use. One. Same as the Blue Potion, only the Red ones cost 68 rupies. A Red Potion will replace a Blue one if you already have it. When you drink a Red Potion it turns blue.
Blue Ring When you "wear" this ring your suit will change color. You only take half as much damage with it than as regular Link. One. You buy it in a store for 250 rupies. If you are having trouble early in the game save up enough rupies for the blue ring, it will make things a lot easier.
Red Ring Better than the Blue Ring, damage is reduced to that of a quarter of usual damage levels. One. Found in the ninth dungeon. The Red Ring replaces your Blue one.
Bomb A small explosive, can be used to harm some enemies, blow holes in the walls of dungeons and in rocks in the Overworld. 8, 12 or 16 (you can increase your capasity by 4 in dungeons 4 and 8) You can get them randomly from enemies, or you can buy them at stores for 20 rupies. You will need to use Bombs to defeat the Dodongos.
Boomerang It's a weapon. You throw it, it comes back to you. One, you can use it infinitely though. You get it in the first dungeon. Boomerangs will defeat very little enemies, but will usually only stun most others. It can also be used to retrieve items, very useful.
Blue (Magic) Boomerang A better version of the boomerang. It travels farther than the regular one. One, infinite uses. You get it in the third dungeon. Replaces the regular Boomerang in your inventory.
Bow It's a bow, once you get it you can shoot arrows at enemies. One. You get it in the fifth dungeon. If you buy arrows ahead of time you can't use them until you get the bow, duh :P
Clock When you get a clock it will freeze all the enemies on the screen and make you invincible for that screen. N/A They appear randomly in battle when you're fighting enemies. Always get the clock as soon as it appears!
Compass It shows the location of the Triforce piece in a dungeon. One per dungeon. There is one hidden in every dungeon. Check the Dungeon Maps and Walkthrough sections for more specific help. One of the rooms next to the Triforce piece contain the boss enemy (most of the time), be careful.
Fairy A fairy will fly around the screen when it appears. If you capture a fairy it will refill 3 heart containers. N/A After defeating enemies a fairy may randomly appear. There are fairies located in lakes throughout the Overworld who will refill all your health.
Food/Bait You have to give this to a certain Molblin NPC in order to continue onward in dungeons 3. One. You can buy it at stores for either 60 or 100 rupies. According to the manual you can put your bait down on the ground and some monsters will be attracted to it. I've never actually tried it myself, seems like a waste of money :P
Heart This is heart, a unit of your life. Every heart you get...fills one empty heart in your life bar! The shock! :P N/A You get extra single hearts by defeating enemies, it will randomly appear. You can buy it at stores for 10 rupies. Note: These are different from the "Heart Containers," which extend your life bar by one heart. A regular heart merely fills up an existing heart.
Heart Container If you find a Heart Container it will extend your life bar by one heart. Invaluable. There are 13(doublecheck) Heart Containers in Hyrule, not counting the three you begin with. You get them at the end of the first eight dungeons. There are also five hidden Heart Containers in the Overworld. Go to the Heart Containers section if you need help finding any.
Key A key will open one locked door in a dungeon. There are at least as many keys as there are locked doors. You don't honestly expect me to count them all do you? :P Sometimes a key will be dropped by an enemy when you defeat them, but usually you are rewarded a key by defeating all the enemies in a room. You can buy a key at some stores for 80 or 100 rupies, but if you use my shrine you won't have to :P
Large (Magical) Shield A much larger version of your regular shield. Can block more objects. One. It has to be purchased. You can buy it at stores for 90, 130, or 160 rupies. Be careful, if a Like-Like sucks you in, you will lose your Magical Shield and have to re-purchase it.
Letter An old man will give you a letter which you are to return to an old woman. When you do that you can buy Life Potions! One. Go to my Overworld Map for its location. The Life Potions will take the spot of the Letter when you give it to the old lady.
Lion (Magical) Key This is a way better version of the normal keys found in the dungeons, this one does not break after one use :P One key, but can be used for opening unlimited doors. You get it in the eight dungeon. You'll need it in dungeon 9, unless you want to buy a lot of keys.
Magic Book Enhances the magic wand to cause a fire when the beam hits something. One. You get it in the fourth dungeon. You need the Magic Wand (dungeon 8) to benefit from it.
Magic Wand (Rod) Shoots a beam to hurt baddies with. One. You get it in the eighth dungeon. When you have the book the wand will cause a fire when the beam hits something.
Map Shows you the minimap of the dungeon in the top-left of the screen. One per dungeon. There is one hidden in every dungeon. You can see them in the Dungeon Maps and Walkthrough sections. Sometimes there are hidden rooms that are not on the minimap.
Power Bracelet With the bracelet you can use an underground travel system. See the Overworld map section for more details. One. It's found on the Overworld map, see the Overworld map section for more details. You'll have to push a rock in the passage locations to enter the underground passageways.
Raft You can travel across water at some locations on the Overworld map with this. One. You get it in the fourth dungeon. In the locations where you use the raft there's a ramp on which you have to walk.
Recorder Well... you can whistle on it. :) When you use it a tornado appears bringing you to the entrance of a random dungeon from the first quest. One. You get it in the second dungeon. It opens the entrances to dungeon 3, dungeon 6, and 2 heart containers.
Step Ladder With it you can cross small patches of water. One. You get it in the sixth dungeon. You can get a heart container on the Overworld map with it, see the Extra Heart Containers section for more information.
Sword Your basic slashing equipment, you can't do it without this one. :) One. In the cave in the screen where you start your quest. You can shoot with it if you have full health.
White Sword Same as the basic sword, only does twice the damage. One. In the cave on top of the waterfall, see the Overworld map section for the exact location. You can shoot with it if you have full health.
Magical Sword Same as the basic sword, only does four times the damage. One. In a secret cave in the mountains, see the Overworld map section for the exact location. You can shoot with it if you have full health.
Triforce Piece Well nothing really, you need all 8 pieces to enter the ninth dungeon. 8 There's one at the end of each dungeon. Restores your life and transports you back to the Overworld map.