Glossary.
Not sure what something means? Here's a quick reference for terms you'll see in Parallax.
The Basics
The big ideas behind how Parallax helps you learn
Spaced Repetition
Instead of cramming everything at once, you review cards at increasing intervals—just before you'd forget them. This is how Parallax helps you actually remember long-term.
Example: A new card might come back after 1 day, then 3 days, then a week, then a month...
FSRS
The algorithm that powers Parallax (stands for "Free Spaced Repetition Scheduler"). It figures out when you should see each card based on how well you're learning it.
Forgetting Curve
The reason cramming doesn't work: without review, you forget most of what you learn within days. Parallax is designed to beat this curve.
Behind the Scenes
You don't need to understand these, but here's what they mean if you're curious
Stability
How strong your memory of a card is. Higher stability means you can go longer before needing to review it again.
Example: A card with 30-day stability is well-learned. A card with 1-day stability needs more practice.
Difficulty
How hard a particular card is for you. Some cards are just harder to remember—the algorithm notices and adjusts.
Retrievability
The chance you'd remember a card right now if we showed it to you. Parallax tries to schedule reviews so this stays around 90%.
Mastery Levels
How Parallax tracks your progress on each card
New (Mastery Level)
Cards you've created but haven't studied yet. They're waiting for their first review.
Learning (Mastery Level)
Cards you've started studying but are still fresh. You'll see these frequently until they stick.
Growing (Mastery Level)
Cards you're getting the hang of. Reviews are less frequent now, but the memory isn't rock-solid yet.
Mastered (Mastery Level)
Cards you really know. You might only see these once a month—they're in your long-term memory.
Review Ratings
The buttons you tap when reviewing a card
Again
Tap this when you completely forgot the answer. The card will come back soon so you can try again.
Hard
Tap this when you got it, but it took real effort to remember. You'll see it again fairly soon.
Good
Tap this when you remembered correctly without too much struggle. This is the "normal" rating.
Easy
Tap this when you knew it instantly, no thinking required. The card will be pushed further into the future.
App Concepts
How things are organized in Parallax
Card
A single thing you want to learn—like a vocabulary word. Cards have a front (the question) and a back (the answer).
Set
An ordered group of Cards for one Subject. Public Sets can be added to My Sets without copying the shared Cards.
Example: A Korean travel Set might contain the phrases you want to review for a trip.
Subject
A maintained area of knowledge that contains canonical Cards and public Sets.
Example: Korean can be a Subject inside the Languages Discipline.
Front to Back
Studying by seeing the front of the card first. For language learning, this means seeing the foreign word and trying to recall the translation.
Example: See "hola" → recall "hello"
Back to Front
Studying by seeing the back of the card first. For languages, this means producing the foreign word—usually harder than recognition.
Example: See "hello" → recall "hola"
Bidirectional Learning
Learning cards in both directions. You might recognize a word easily but struggle to produce it—Parallax tracks these separately.
Due Cards
Cards that are ready to review right now. The algorithm decided it's time to see them again.
Study Session
A focused time where you review due Cards in Schedule or inside one Set.