Creatures on the island can be tamed and used for various purposes. Some uses for tamed animals include riding, item transportation, hunting, harvest, and defending your home while you are offline. Most items placed in a tamed creature's inventory will take much longer to spoil than they usually.
To tame creatures in Ark Survival Evolved, there are different ways for each animal. Some animals require something called a passive tame, which is were you feed it it's favorite food without knocking it unconsious. The second way is an agressive tame, which is were you knock the creature unconsious and put it's favorite food in its inventory slot.