Brewing

Brewing is the method by which many potions are made in Minecraft. Jeb has said that it will probably not come out in 1.9 (It is implemented in 1.9 prerelease 3), possibly pushing the release to 1.10. Originally potions were to be brewed in Cauldrons but Jeb later tweeted that he and Notch had come up with a different brewing method and potions are now made in Brewing Stands.

History
According to code found in the Beta 1.9 Pre-release 2, Potions are brewed by adding water to a Cauldron, and then combining ingredients. Ingredients in the correct combination would confer beneficial potion effects with no downside, or additional negative status effects. In 1.9, there will be a Brewing Stand to brew potions in, while the Cauldron is now used to hold the water needed for brewing.

In the Beta 1.9 Pre-release 2 there were many ingredient combinations which resulted in many different potion effects. Currently the system is simplified from 150 different potions to an estimated 22. For example the potions Nausea, Blindness and Invisibility can no longer be created. Under the original Cauldron base system Jeb recommended certain "'clean' potions that don't require a lot of work." The Brewing Stand will brew a single ingredient for 30 seconds into the bottle(s).

In Beta 1.9 Pre-release 4 Splash Potions were introduced. "You can turn any potions into a splash potion by brewing Gunpowder into a potion (even Even Instant Health II). It appears in a different shaped flask. Instead of drinking it, you throw it like a grenade."

Potion ingredients
Necessary to make potions: The following are the main bases and add special effects to regular potions:
 * Water Bottle: fill glass bottle with water
 * Fermented Spider Eye: gives negative effects and downgrade upgraded effects.
 * Glowstone (Dust): upgrades effects, but decreases their duration.
 * Nether Wart: neutral base for regular potions.
 * Redstone dust: increases the duration of effects, but downgrades upgraded effects.
 * Gunpowder: makes potions into throwable splash potions.

The following are the main ingredients required to give the potions their special effect:
 * Blaze Powder: for strength.
 * Ghast Tear: for regeneration.
 * Magma Cream: for fire resistance.
 * Spider Eye: for poisoning.
 * Sugar: for speed.
 * Glistering Melon: for instant health.

Base Potions
Base potions are required before advanced potions can be brewed.

Trivia

 * 1 ingredient is enough to create up to 3 potions.
 * Upgrading an Instant Health Potion (I) with glowstone dust has no downsides.
 * Upgrading a Fire Resistance Potion with redstone dust has no downsides.
 * Although it has been said by Jeb that in the 1.9 pre-release 3 there were 161 possible different potion combinations and there may be 2,653 in the future, in the 1.9 pre-release 3 it was only possible to make 22 different potions without the use of external programs. 19 of those 22 potions had effects, and 8 different attributes were available.