Brewing

Brewing is the process of creating potions, splash potions, and lingering potions by adding various ingredients to water bottles in a brewing stand. $$, brewing can also create medicines.

Base ingredients and modifiers
Base ingredients are ingredients that can be added directly to a water bottle and are the starting point of all potions. Nether wart is the most fundamental of the base ingredients, as it is required to make the vast majority of potions.

Modifiers are ingredients used to alter the properties of a potion or to change a potion effect into a different one. The fermented spider eye is unique in that it is the only modifier that can convert a water bottle directly into an effective potion.

Enhancement: Generally, upgrading a potion involves a trade-off between duration and potency. A potion with an enhanced effect has shorter duration, and a potion with extended duration cannot have an enhanced effect. However:
 * Upgrading the effect of a potion that has no time parameter (e.g. Instant Health) with glowstone involves no trade-off.
 * Upgrading the time of a potion that has no level II effect (e.g. Fire Resistance) with redstone involves no trade-off.

Corrupting effect: A fermented spider eye changes a potion's base effect, often reversing it or producing a negative potion.
 * A corrupted potion usually does the opposite of the original potion.
 * Corrupting an enhanced or extended potion into an effect that supports the modifier results in a potion with the same modifier applied.
 * Corrupting an enhanced potion of Poison/Healing results in a basic potion of Harming. Enhanced potions of Leaping or Swiftness cannot be corrupted.
 * A potion of Invisibility is considered a "corrupted" version of a potion of Night Vision.

Splash and lingering potions: Any potion can be turned into a splash potion, and subsequently, a lingering potion. Splash and lingering potions can be used best for affecting other entities.
 * Splash potions and lingering potions can be modified in the same manner as their normal counterparts. For instance, a splash water bottle can be brewed with any of the base ingredients; the result remains a splash potion.
 * Some extended/enhanced splash and lingering potions cannot be brewed from their extended/enhanced potion/splash potion counterparts, respectively (e.g. Regeneration + → Splash Potion of Regeneration +).
 * $$, splash potions' effects have only three-fourths of the duration of the drinkable form. For example, a drinkable potion effect of 8:00 is reduced to 6:00 as a splash potion. $$, splash and drinkable forms have the same duration.
 * Lingering potions have only one-fourth of the duration of the drinkable form. For instance, a drinkable potion effect of 8:00 is reduced to 2:00 as a lingering potion.

Effect ingredients
Effect ingredients imbue an awkward potion with a particular effect but do not alter potion duration or intensity. When added directly to a water bottle, most of these ingredients produce a mundane potion. The exceptions to this are golden carrot, pufferfish, turtle shell, and phantom membrane, which cannot be added directly to a water bottle.

Base potions
Base potions are potions without effects, brewed by adding a single base ingredient to a water bottle. Of these, only the awkward potion can be imbued with an effect ingredient to produce a potion effect.

Effect potions
Effect potions are primarily created by adding an effect ingredient to an awkward potion, which is created by adding nether wart to a water bottle. Certain effects require a potion to be corrupted by a fermented spider eye. The potion of Weakness can additionally be created by simply adding a fermented spider eye to a water bottle &mdash; and it is the only potion that can be brewed without nether wart.

Undead mobs react differently to effects than other mobs. They take damage from potions of Healing, gain health from potions of Harming, and are unaffected by potions of Poison and Regeneration.

Cures
Cures are brewed from awkward potions using different elements. Drinking these removes the specified bad effect. They cannot be modified into splash, lingering, extended, or enhanced versions.

Unbrewable potions
The potion of Luck and the potion of Decay cannot be brewed, and can be obtained only through commands or the Creative inventory.

Trivia

 * Although Jeb said that in Java Edition Beta 1.9 Prerelease 3 there would be 161 possible different potion combinations with 2,653 in the future, in the actual third pre-release only 22 different potions could be made without the use of external programs. Of those, 19 potions had one of 8 different effects.
 * By modifying the item NBT using an editor or commands, it is possible to get a potion that cannot be upgraded into a splash potion.
 * Unlike crafting, smelting and stonecutting, there is no in-game recipe book for brewing.
 * Destroying a brewing stand while still having a full 8 amounts of blaze powder drops the powder with it.