A credit score is just a trust score — and the rules of the game fit on one card.
Your credit score is a number from 300 to 850 that tells lenders how reliably you repay. It decides your apartment application, your car loan rate, sometimes even a job screening. And the system never hands you a manual. Here's the manual.
What actually moves the score
In order of weight
Payment history (~35%) — did you pay at least the minimum, on time, every time
Utilization (~30%) — how much of your credit limit you're using; under 30% is good, under 10% is great
Age of credit (~15%) — older average accounts help; this is why you keep your first card forever
New credit + mix (~20%) — opening many accounts fast looks thirsty; a variety of account types mildly helps
The trap the card companies are counting on
The minimum payment is not a suggestion for how much to pay — it's the least you can pay without penalty. Carry a balance and interest (often 20%+ APR) compounds against you. The move: use the card like a debit card, pay the full statement balance every month, pay zero interest, and let the score climb anyway. You do not need to carry a balance to build credit. That's a myth that costs people thousands.
20%+typical credit card APR. There is no investment that reliably beats it — which is why paying off card debt IS the best investment available to most people.
Starting from zero? Secured cards and student cards exist exactly for you. Becoming an authorized user on a parent's old, well-paid card can also jumpstart your history — a very normal family move that nobody talks about out loud.
Watch
Knowledge check
Not a pop quiz — nothing is graded, and you can retake it forever. It exists so you know what stuck.
Question 1 of 4
The single biggest factor in your credit score is…
Flashcards
The unit in six cards — the version that stays with you after the tab closes.
Card 1 of 6
Do
Homework: your life
Check your credit score for free this week (your bank app almost certainly shows it). No score yet? Look up one secured or student card and read its terms — just read, no application needed.