Potion

Potions are a future craftable food items that confer specific effects in Minecraft. Potion recipes have not yet been defined as of the Beta 1.9 Pre-release. But Potion effects were introduced in Beta 1.8.

History
Alchemy was first hinted at in July 2010, when Notch explained why redstone ore disintegrates into "dust". He states that dust will be used later in potions.

A couple months later, Notch did a Q&A session on Reddit. He was asked about Alchemy, and responded "Oh Yes! Definitely!". All of his posts in that thread are now deleted, but records can be found in other places.

Potion effects were introduced in Beta 1.8. Jeb later tweeted a potion effects screenshot taken from within from Beta 1.9 Pre-release 2. The image shows potion effects, potion levels, and potion duration, as well as what appear to be potion bottles or vials.