This guide will let you know how to Find Slimes in Minecraft.
You can find the slimes in the highly common swamp biome, so you will need to start by finding one of these.
Once you find one, you have to wait until nighttime because slimes will spawn. At night time, walk into the centre of the swamp, and it is where slimes are most likely to spawn.
Once deep in, you will begin to find them in various sizes.
The big slimes will turn into smaller slimes when killed.
The smallest slimes will drop balls of slimes, and they can also do no damage to you.