On October 31st 1981, Lily and James Potter gave their lives for their son Harry. Their love and sacrifice (especially Lily's) enabled him to survive the Killing Curse even as a baby, kept him safe from Voldemort and lesser evils for many years and gave him the strength to keep fighting as he grew.
From the book:
... on the night of 31 October 1981,
Lily and James Potter lost their lives.
Their son, Harry, remains the only wizard ever to have survived the Killing Curse.
This house, invisible to Muggles, has been left
in its ruined state as a monument to the Potters
and as a reminder of the violence
that tore apart their family.

Lily and James Potter lost their lives.
Their son, Harry, remains the only wizard ever to have survived the Killing Curse.
This house, invisible to Muggles, has been left
in its ruined state as a monument to the Potters
and as a reminder of the violence
that tore apart their family.

Thirty years. RIP, James and Lily Potter.