Apple

Apples are food items that can be eaten by the player.

From trees
Oak and dark oak leaves have 0.5% ($1/200$) chance of dropping an apple. This amounts to approximately 25% chance to get an apple from an oak tree and 60% chance from a dark oak tree.

In the pocket edition, the chance is higher.

From loot chests
Apples can be found in chests found in strongholds and villages, as well as in the bonus chest.

From trading
Villager farmers may offer to sell apples in exchange for emeralds. 5 apples can be bought per emerald as one of their third tier trades.

Usage
Eating an apple restores and 2.4 points of saturation.

As a crafting ingredient
An apple can be used to craft a golden apple or an enchanted golden apple.

Video
Note: The video shows golden apples being crafted with gold nuggets. This is outdated, as they are crafted with ingots on PC and Pocket editions.

Trivia

 * The sprite of red apples was the same as used in Notch's game Legend of the Chambered.