Achilles was born to Peleus and King of the Myrmidons and Thetis. His Mother a nymph tried to make him immortal by dipping him into the River Styx, but she didn't realize that she was only dipping him into the river up to his ankles, leaving them unprotected.
Achilles was given a choice by the gods to either choose a long life filled with happiness or a short life with glory and be remembered as a hero, and Achilles choose to have a short life and be remembered as a hero.
Achilles decided that he will choose a life of glory. He would become Ancient's Greece most famous hero, which led him to fight in the city of Troy. Achilles refused to fight, so his friend Patroclus wore his armor for in battle.
Patroclous was killed by a warrior named Hector, Achilles seeing his friend killed sent him into a angered rage.
Achilles killed Hector and Hector's father begged him to spare the body so they could bury it.
After the Trojan War, Achilles was killed by Paris, he/she killed him by shooting him in his only weakness... his "Achilles Heel".