Lily Potter used a very powerful and ancient magic to protect her son Harry from Lord Voldemort. She sacrificed her own life willingly and out of deep, pure love to save Harry, who was only a baby at that time. This act of love created a magical barrier around Harry that shielded him from harm and made it impossible for Voldemort to kill him directly. ¹⁵

This magic was not a spell that Lily cast with a wand or an incantation, but a natural and instinctive reaction that came from her heart. It was a rare and special kind of magic that Voldemort could not understand or overcome, because he had never experienced love himself. ³⁶

Lily's protection flowed in Harry's veins and left a mark on his forehead, the lightning-shaped scar that was the result of Voldemort's killing curse backfiring. ³⁴ The protection also extended to the place where Harry lived, as long as he could call it home and as long as he was a child. Dumbledore used this magic to cast a charm on the Dursley's house, making it a safe haven for Harry until he turned seventeen. ⁴

However, the protection also had a weakness. When Voldemort used Harry's blood to rebuild his body, he unknowingly took a part of Lily's protection into himself. This made Harry and Voldemort connected by blood, and allowed Harry to survive another killing curse in the forest. It also gave Harry's allies a temporary protection from Voldemort's spells, as long as Harry was willing to die for them. ⁴

Lily's protection was a powerful and long-lasting counter-charm that saved Harry's life many times and helped him defeat Voldemort in the end. It was a testament to the power of love, which is the strongest magic of all.