Razz Berry

A Razz Berry is an item that can be found at Trainer Level 8 and higher. They can be obtained from PokéStops or by reaching certain levels.

Details
Feeding this berry to a Pokémon while trying to capture it increases the chance of success.

The in-game description of the item is misleading. It states that feeding it to a Pokémon "on your next throw" will make it easier to catch. The effect actually lasts until the Pokémon enters a Poké Ball at least once. If the Pokémon seems to be captured, but escapes the ball, the effect of the berry wears off, and another must be used. If the Pokémon does not enter the ball, such as if the player's throw misses, the effect does not disappear.

In-game description
Feed this to a Pokémon, and it will be easier to catch on your next throw.

Trivia

 * Razz Berries become available from PokéStops at Level 8.
 * They are named after a raspberry.
 * Only one Razz Berry can be used at a time. After an unsuccessful capture, the player may use another one.