Love is described by Albus Dumbledore as the deepest and most powerful form of magic, one that is poorly understood and consistently underestimated by those who traffic in the Dark Arts, particularly Lord Voldemort. Its most significant applications in the series revolve around acts of selfless sacrifice.
Love as a form of magic cannot be learned or taught in a conventional sense, as it is not a spell that can be mastered with practice. It is an emotion-driven, instinctual magic that arises under very specific and dire circumstances. Albus Dumbledore considered it a power that Lord Voldemort could never grasp due to his inability to understand or feel love. There is no known counter-spell for sacrificial protection. However, its effects can be circumvented. Lord Voldemort managed this by using Harry's own blood—which contained Lily's magical protection—in the regeneration potion that restored his body. This act incorporated the protection into Voldemort himself, allowing him to touch Harry without pain. Unknowingly, this also tethered Harry's life to Voldemort's, preventing Harry from being truly killed by Voldemort as long as the Dark Lord lived.
The English word “love” originates from the Old English lufu, meaning “love, affection, friendship.” Its roots are common in Germanic languages. In the context of the wizarding world, its use for the most powerful form of magic highlights the theme that fundamental human emotions hold a power that can surpass any complex spell or dark curse.