FICO score
A FICO score is a three-digit credit score (300–850) created by the Fair Isaac Corporation that lenders use to gauge how you've handled borrowing. It is built from five factors, with FICO's published weights (myFICO): payment history (35%), amounts owed (30%, including credit utilization), length of history (15%), new credit (10%), and credit mix (10%); FICO says the importance of these categories may vary from one person to another.
Why it matters
FICO says 90% of top US lenders use its scores, so it is often the score a lender checks — though each lender decides approvals and rates on its own criteria. One payment 30+ days late can lower a FICO score; how much depends on the rest of your credit report.
Example
With on-time payments and low balances, someone might sit in the "good" range (670–739); a single 30-day-late payment reported to the bureaus can drop that score, and how far depends on the rest of the credit report.