The common and uncommon slots
The bulk of any pack is made up of commons and uncommons. These fill most of the pack and form the backbone of a set, including the Trainer cards and basic Energy that make decks playable.
While they are the least exciting to pull, commons and uncommons are essential for set completion, and many older commons have become surprisingly collectable over time.
The guaranteed rare slot
Every pack guarantees at least one card of rare or higher. In older sets this was often a non-holo rare; in modern sets this slot frequently upgrades into a holo, an ex, or a higher rarity entirely.
This is the slot most people watch, because it is where the value of a pack usually lives.
The reverse holo slot
Modern packs include a reverse holo — a card of any rarity with a shimmering, patterned foil across the whole card rather than just the artwork. Reverse holos give even common cards a premium finish and are a collecting category all of their own.
Chasing the hit
The rarest cards — ultra rares, secret rares and alternate arts — appear far less often than once per pack. Depending on the set, a single chase card might show up only once every several booster boxes.
That scarcity is exactly what makes opening packs exciting, and it is faithfully reflected when you rip a pack on PackRip.