Credit Score
A credit score is a number, usually between 300 and 850 in the United States, that summarizes how reliably a person has repaid debt. It is calculated from the credit report: payment history, balances, the age of accounts and recent applications.
Landlords check credit next to income. The 3x rent rule answers whether you can pay, and the score suggests whether you will. Many properties publish a minimum score in their screening criteria along with the income multiple.
The two can offset each other. A strong score sometimes earns approval for an applicant slightly under 3 times the rent, and a weak one can lead to a request for a co-signer or a larger deposit even when income is well above the line.