Razz Berry

Razz Berry is an item that can be found at trainer level 8 and higher. Once at high enough level, they can be obtained from PokéStops or by leveling up.

The ideal usage is when you find a possibly difficult Pokémon to catch, so you feed it a Razz Berry from your inventory which will increase the success chance when you attempt to capture.

Description
Feed this to a Pokémon, and it will be easier to catch on your next throw.