Before a bank lends you anything — a card, a car loan, a home loan — it asks a credit bureau one question: how has this person repaid borrowed money in the past? The answer comes back as a credit report, summarised into a three-digit number. In India the best-known version of that number is the CIBIL score, from TransUnion CIBIL, and it runs from 300 to 900.
CIBIL is not the only bureau. Experian, Equifax and CRIF High Mark each maintain their own report and their own score, built from data the same lenders send them every month. Your numbers will differ slightly between bureaus, which is normal and not a sign that something is wrong.
The score is a compressed summary of the report, and the report is a month-by-month ledger: which accounts you hold, what their limits and balances are, and whether each payment arrived on time. Lenders send that data regularly, so the score is a moving picture rather than a one-time verdict.
Broadly, the bands above are how lenders read it — but each lender sets its own cut-offs, so treat them as a rule of thumb rather than a law. A score of 780 does not entitle anyone to a specific card, and no honest site can tell you that it does.