The first harcover book of
character races,
classes, equipment, and
spells for
Advanced Dungeons and Dragons. One of the original, core
AD&D rule books.
A later volume,
Unearthed Arcana, would add some character options and spells, but it did not compare to the solid foundation of the
PH. I feel safe in asserting that AD&D would not be the same game without the standard
PH character races of
dwarf,
elf,
human,
gnome, halfling, and even
half-orc. Likewise, the fourfold
class structure of
fighter,
thief,
cleric, and
magic-user is essential, oddities such as the
monk and
psionicist classes notwithstanding.