sean-zevran:

BUFFY SLAYS 20 – TOP 20 HIGHEST-RATED EPISODES ON IMDB

16. 3×21 – Graduation Day: Part 1 (May 18, 1999) | IMDB Rating: 9.0

All the demons that walk the earth are tainted, are human hybrids, like vampires. The Ascension means a human becomes pure demon.